Ubiquitous means

If the sound of the bells could be heard in the entire community, it means the sound was heard throughout or across the entire community. The word "throughout" indicates that the sound reached all parts of the community. The options "thorough," "thought," and "through" do not convey the same meaning in the context of the sentence.

The verb "assemble" means to bring together or gather in one place or group. It implies the act of collecting or uniting individuals or things in a coordinated manner. Therefore, "assemble" is the correct word that describes the action of gathering together. The options "appearance," "assembly," and "semblance" do not convey the same meaning as "to gather together."

The verb "effect" means to bring about, cause, or accomplish something. It refers to the action of making something happen or producing a desired result. The word "effect" is often used to describe the act of implementing or causing a change or outcome. The options "affect," "expect," and "accept" do not convey the same meaning as "to bring about, cause to happen; to accomplish; to make."

Surveillance refers to the act of closely monitoring or observing someone or something, typically for the purpose of gathering information or ensuring safety. It involves systematic observation, often done in a discreet or secretive manner. The options "isolation," "cognition," and "assessment" do not specifically convey the meaning of placing someone or something under observation.