Final answer:
The child is most likely to have Chickenpox (option A).
Step-by-step explanation:
The child is most likely to have Chickenpox (option A). Chickenpox is a highly contagious viral infection caused by the varicella-zoster virus. It is characterized by a vesicular rash that starts on the trunk and spreads to the rest of the body, including the face, arms, and legs. The rash typically appears about 10-21 days after exposure and lasts for about 7-10 days. Other symptoms of chickenpox include fever, headache, and fatigue.