(i) Whenever milk is kept in front of a child, he/she starts crying. (ii) Children cry if they are hungry. (iii) Unhappy children are hungry.

Lets eliminate options one by one-
Option A: Child is hungry, So, from (ii) child is crying, but we cannot say anything about the child liking milk or not.
Option B: A child is crying, but from this we cannot say anything regarding the child being hungry or unhappy.
Option C: The statements are not speaking about the happy child.
Option D: Unhappy children are hungry and hungry children cry. So choice (D) is most logically supported.