Answer: Python Puzzler #3840

The answer is B. The program prints:

moo

This answer was checked by running the program for real.

Why?

A dictionary stores pairs: a key and its value. sounds["cow"] looks up the key ‘cow’ and gives back its value.

Trace table

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

key	value
cow	moo
frog	ribbit
dog	woof
sheep	baa

The code again

sounds = {
    "cow": "moo",
    "frog": "ribbit",
    "dog": "woof",
    "sheep": "baa",
}
print(sounds["cow"])