Answer: Python Puzzler #3612

The answer is B. The program prints:

52

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
12	yes	12
42	yes	42
37	no	42
52	yes	52
19	no	52

The code again

numbers = [12, 42, 37, 52, 19]
biggest = 0
for n in numbers:
    if n > biggest:
        biggest = n
print(biggest)