Slip (one’s) mind

Do you know the English expression “slip (one’s) mind“? Read the conversation below. Can you guess the meaning?

Jay: Did you take the money to the bank this morning?

Fiona: I planned to, but it slipped my mind. I’ll do it tomorrow morning.

Does it mean:

a) be forgotten

b) be remembered

c) be memorized

d) be cancelled

The answer is below!↓

 

Answer: a) be forgotten