How does sancho know which locker is Williams The gym lady told him
Bolds lead him to it
Sancho looked it up in the gym records
There is a sign with his name on it

Sancho was able to figure out which locker belonged to Williams because There is a sign with his name on it.

As they were in the gym, Sancho was able to spot the locker that belonged to Williams thanks to his name being written on the locker. When they open it, they find a letter.

In conclusion, option D is correct.

Find out more on Sancho and Bolsa at  link.

The way in which Sancho identifies William's locker is:

In their search, Sancho and Bolsa decide to go to the gym, a place frequented by William and which can give them clues about his whereabouts, however, all they can get from the people there is information they already know, for which, they decide to check his locker, which has his name on it and makes it easy for them to find him.

If you want to learn more about Sancho and Bolsa, you can visit the following link: link

ok i dont know what b says but d is the only one that sounds some what like an aperitivo

same as the person below me