Answer: Python Puzzler #950

The answer is C. The program prints:

[3, 6, 9, 12, 15]
What the program prints
Checked by running the program for real.

Why?

range(3, 18, 3) counts from 3 in steps of 3 and stops before 18.

The code again

print(list(range(3, 18, 3)))

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