Answer: Python Puzzler #1060

The answer is C. The program prints:

[9]

Checked by running the program for real.

append adds one item to the end of the list each time round the loop. The loop runs for n = 3.

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

n	n * 3	results so far
3	9	[9]

results = []
for n in range(3, 4):
    results.append(n * 3)
print(results)

Try it: change one number in the program and predict the new output before you run it.