The answer is A. The program prints:
plum

Why?
A negative position counts from the end: -1 is the last item, -2 the one before it. So -3 means item number 3 from the end.
Trace table
A trace table follows the program step by step. Here’s this one:
| position | negative position | item |
|---|---|---|
| 0 | -4 | pear |
| 1 | -3 | plum |
| 2 | -2 | carrot |
| 3 | -1 | mango |
The code again
basket = ["pear", "plum", "carrot", "mango"]
print(basket[-3])
Try it: change one number in the program and predict the new output before you run it.