Answer:
D. ¿Te gusta jugar?
Explanation:
Options A and B are a bit impolite to ask.
A means, "Do you like to eat?"
B means, "Do you like to talk?"
This may make it seem as if the grandfather eats or talks too much.
C would not fit in this situation as it is asking, "I like to eat?"
D asks, "Do you like to play?" This is a perfect question for the coach to ask, because the grandfather's granddaughter enjoys playing; The grandfather may take interest in playing and may have even gotten his granddaughter into the sport.