Answer:
I'd say option D: Carol, be sure to watch the child, please.
Explanation:
Because it would include the characters name in the story otherwise the dialogue wouldn't really progress forward and you wouldn't know the character.
It is the first one: Be sure to watch the sick child carefully, please.
BIG OOOOOOOOOOOOOOOOOOOOOOOOOOOF
Answer is C, a textbook.
the answer could be explicit but i could be wrong.