The answer is D. The program prints:
bit-pong-ping-beep
This answer was checked by running the program for real.
Why?
join glues the items of a list together, putting ‘-‘ between each pair.
The code again
sounds = ["bit", "pong", "ping", "beep"]
print("-".join(sounds))
Try it: change one number in the program and predict the new output before you run it.