How about 'I will take the money' since pegar can mean 'take.'
It is also right.
I will collect the money was marked wrong
Pegar is one of the very tricky verbs. It can can mean so many things. Others are tirar and levar,
'I will pick up the money' was marked wrong. Given the wealth of different meanings possible for pegar, I should have thought that 'pick up' correctly reflected the spirit of this phrase.