The answer is A. The program prints:
[13, 14, 15]

Why?
append adds one item to the end of the list each time round the loop. The loop runs for n = 3, 4, 5.
Trace table
A trace table follows the program step by step. Here’s this one:
| n | n + 10 | results so far |
|---|---|---|
| 3 | 13 | [13] |
| 4 | 14 | [13, 14] |
| 5 | 15 | [13, 14, 15] |
The code again
results = []
for n in range(3, 6):
results.append(n + 10)
print(results)
Try it: change one number in the program and predict the new output before you run it.