The recommended children's dosage of Keflex is 25 to 50 mg/kg/day in divided doses. The maximum daily safe dosage for a child weighing 42 lb is: Round to the nearest tenth.

(Number Only, do not enter mg, kg, or day with your answer)

The correct answer is choice A. Infection or inflammation close to the site.

Choice A rationale:

Tender, enlarged, and warm lymph nodes are indicative of infection or inflammation in the nearby area. Lymph nodes are part of the immune system and can become enlarged and tender when fighting off infections in their drainage area.

Choice B rationale:

While cancer can cause lymph node enlargement, it is less likely in children, and the question doesn't provide any other context to suggest cancer as the primary explanation.

Choice C rationale:

Local scalp infection might cause enlargement of the lymph nodes in the neck, but it would not be the best explanation for tender, enlarged, and warm cervical lymph nodes. Infections or inflammation close to the site of lymph node involvement are more likely.

Choice D rationale:

Infection or inflammation distal to the site wouldn't directly explain the tenderness, warmth, and enlargement of the cervical lymph nodes. Lymph nodes generally react to infections or inflammation in their drainage area.

Choice A rationale:

Hypoparathyroidism is not associated with exophthalmos. Hypoparathyroidism is a condition where the parathyroid glands produce insufficient parathyroid hormone, leading to low calcium levels in the blood. This condition doesn't directly affect the thyroid gland or cause exophthalmos.

Choice B rationale:

Exophthalmos, also known as protruding or bulging eyes, is a classic symptom of hyperthyroidism. Hyperthyroidism is a condition where the thyroid gland produces excessive amounts of thyroid hormones. These elevated hormone levels can lead to a variety of symptoms, including increased metabolism, weight loss, nervousness, and protruding eyes due to inflammation of the eye muscles and tissues behind the eye.

Choice C rationale:

Hyperparathyroidism involves the overactivity of the parathyroid glands, leading to excessive production of parathyroid hormone (PTH) and elevated calcium levels in the blood. While elevated calcium levels can have various effects on the body, exophthalmos is not a typical manifestation of hyperparathyroidism. The condition is more commonly associated with bone and kidney issues.

Choice D rationale:

Hypothyroidism, the underproduction of thyroid hormones by the thyroid gland, is not linked to exophthalmos. Instead, hypothyroidism is known for causing symptoms such as fatigue, weight gain, cold intolerance, and slow heart rate. Exophthalmos is a characteristic sign of hyperthyroidism, not hypothyroidism.