Meaning of "let somebody down"

[carola]

English Idioms and Expressions, Elementary Level

ESL/EFL Test #11 "Expressing Emotions", question 6

I wish I could trust you again, but all that you ever did to me was to let me down.

(a) to make me cry
(b) to make me angry
(c) to despise me
(d) to disappoint me

English Idioms and Expressions, Elementary Level

ESL/EFL Test #11 "Expressing Emotions", answer 6

I wish I could trust you again, but all that you ever did to me was to disappoint me.

Correct answer: (d) to disappoint me
_________________________

is my answer correct?

[Conchita]

Yes, as indicated in the test answer, you chose the correct option:

If you let someone down, you disappoint them, you fail to help them or you leave them in the lurch:

We won't let you down.
A true friend will never let you down.