Which of the following sentences is correctly punctuated?

A topic sentence is the main idea or point of a paragraph. It serves as a guide to the reader, telling them what the paragraph is going to be about. A topic sentence should be clear, concise, and focused on a single idea, and it should summarize the main point of the paragraph. Therefore, the correct answer is A.

In the given sentence, "the class" is a singular noun and requires a singular possessive pronoun. "Its" is the correct form of the possessive pronoun "it" to use with a singular noun, as opposed to "it's," which is a contraction of "it is" and would not be appropriate in this context. "They're" is a contraction of "they are" and would not be appropriate because "class" is singular, not plural.

The word that defines "subterranean" based on the prefix "sub-" is B. Underground.

Choice B: "Whenever the boys played in the rain, they came home with muddy clothes."

This is a complex sentence. "Whenever the boys played in the rain" is a dependent clause because it cannot stand alone as a complete thought, and "they came home with muddy clothes" is an independent clause because it can stand alone. The sentence does not contain two independent clauses joined by a coordinating conjunction (which would make it a compound sentence).

Choice D: "She wanted to go to the beach after she left work."

This is also a complex sentence. "She wanted to go to the beach" is an independent clause, and "after she left work" is a dependent clause because it cannot stand alone as a complete sentence.

To clarify:

• Complex sentence: Contains an independent clause and at least one dependent clause.
• Compound sentence: Contains two independent clauses joined by a coordinating conjunction (like "and," "but," or "or").

Thus, both B and D are complex sentences, but B is the most accurate answer in many tests as it clearly demonstrates the use of a dependent clause ("Whenever the boys played in the rain") followed by an independent clause.

This sentence correctly uses a comma before "so" to connect two ideas. The other sentences have missing or incorrect punctuation.

The sentence " There were buffalo in every western territory of the United States as of 1860." requires citation because it presents a claim or fact that is not common knowledge and needs to be supported by a source

Choice A: In this option, the subject "The boys and girl" is a compound subject that includes both "boys" and "girl." The mistake here lies in the verb "is," which is singular. Since the subject is plural due to the presence of "boys," the correct verb should be "are."

Choice B: This choice correctly follows subject-verb agreement rules. The subject "The boy" is singular, so the verb "come" is appropriately singular. Similarly, for "the girls," which is plural, the verb "come" is used in its plural form.

Choice C: Here, the subject "The boys" and "the girls" are connected by "or," indicating a singular choice. However, the verb "sings" is in the singular form, which is incorrect for plural subjects. To maintain agreement, the correct verb should be "sing."

Choice D: In this option, the compound subject "The boys and girl" is again presented. However, the verb "visits" is singular, not in agreement with the plural subject. To ensure proper subject-verb agreement, the verb "visit" should be used.

The final step of the writing process is editing, where the writer reviews and revises their work for clarity, coherence, and correctness.

Option B is the correct sentence, which reads "The building's height was exceeded by its width." This sentence employs standard English spelling, where "exceeded" is spelled correctly, and the apostrophe in "it's" is incorrect, as it should be "its" without an apostrophe.

The sentence that demonstrates proper subject-verb agreement is D. "Physics is a difficult subject to learn." In this sentence, the singular subject "Physics" agrees with the singular verb "is."