Here's a problem to solve: Six puppies were born at the same time. After 6 months, one of the puppies was much heavier than the others. Which of the following is the most likely explanation for difference in size of that puppy?

Among the 4 following options, which is the correct answer?

- A: It ate more food.
 
- B: It was more active.
 
- C: It drank more water.
 
- D: It received more sunlight.
 