The answer is A. The program prints:
3 0

Why?
// divides and throws away the remainder: each friend gets 3 sweets. % gives the remainder: 0 sweets left over.
Trace table
A trace table follows the program step by step. Here’s this one:
| sum | answer |
|---|---|
| 15 // 5 | 3 |
| 15 % 5 | 0 |
The code again
sweets = 15
friends = 5
print(sweets // friends, sweets % friends)
Try it: change one number in the program and predict the new output before you run it.