The answer is D. The program prints:
1

Why?
count goes through the string and counts how many times ‘u’ appears.
Trace table
A trace table follows the program step by step. Here’s this one:
| letter | matches? |
|---|---|
| p | |
| i | |
| x | |
| e | |
| l | |
| (space) | |
| p | |
| u | yes |
| z | |
| z | |
| l | |
| e |
The code again
word = "pixel puzzle"
print(word.count("u"))
Try it: change one number in the program and predict the new output before you run it.