Answer: Python Puzzler #907

The answer is C. The program prints:

[4, 9, 16]

Why?

append adds one item to the end of the list each time round the loop. The loop runs for n = 2, 3, 4.

Trace table

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

n	n * n	results so far
2	4	[4]
3	9	[4, 9]
4	16	[4, 9, 16]

The code again

results = []
for n in range(2, 5):
    results.append(n * n)
print(results)