A 12-month-old receives the MMR vaccine and suddenly develops flushing, tachycardia, and weak peripheral pulses. What is the likely explanation?

Correct Answer: D

Rationale: Anaphylactic shock is a severe allergic reaction characterized by vasodilation, airway swelling, and circulatory collapse, requiring immediate epinephrine administration.

Correct Answer: A

Rationale: Folic acid deficiency leads to megaloblastic anemia with macrocytosis, unlike conditions such as sickle cell disease and beta thalassemia, which cause microcytosis.

Correct Answer: D

Rationale: Noninfectious causes of urethritis do not typically involve trauma or foreign bodies; they more often relate to chemical irritants.

Correct Answer: D

Rationale: Deforestation leads to the loss of biodiversity as it destroys natural habitats for countless species, disrupting ecosystems.

Correct Answer: B

Rationale: Allergic conjunctivitis is not a major risk factor for persistent asthma.