Answer: Python Puzzler #1668

The answer is D. The program prints:

58

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
57	yes	57
58	yes	58
19	no	58
17	no	58
16	no	58

The code again

numbers = [57, 58, 19, 17, 16]
biggest = 0
for n in numbers:
    if n > biggest:
        biggest = n
print(biggest)