Answer: Python Puzzler #3923

The answer is C. The program prints:

43

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
38	yes	38
27	no	38
4	no	38
43	yes	43
18	no	43

The code again

numbers = [38, 27, 4, 43, 18]
biggest = 0
for n in numbers:
    if n > biggest:
        biggest = n
print(biggest)