Answer: Python Puzzler #3593

The answer is A. The program prints:

40

This answer was checked by running the program for real.

Why?

The loop remembers the biggest number it has seen so far, and replaces it whenever it finds a bigger one. This is how computers find the maximum.

Trace table

A trace table follows the program step by step. Here’s this one:

n	n > biggest?	biggest
29	yes	29
31	yes	31
40	yes	40
38	no	40
17	no	40

The code again

numbers = [29, 31, 40, 38, 17]
biggest = 0
for n in numbers:
    if n > biggest:
        biggest = n
print(biggest)