Answer: Python Puzzler #1596

The answer is D. The program prints:

57

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
9	yes	9
17	yes	17
40	yes	40
57	yes	57
49	no	57

The code again

numbers = [9, 17, 40, 57, 49]
biggest = 0
for n in numbers:
    if n > biggest:
        biggest = n
print(biggest)