Difference between gather and collect

[nancy]

Test No. incompl/advan-3 "Credit Card Holders", question 9

This charity was set up to ......... money for the poor.

(a) collect
(b) gather
(c) assemble
(d) convene

Test No. incompl/advan-3 "Credit Card Holders", answer 9

This charity was set up to collect money for the poor.

Correct answer: (a) collect

Your answer was: incorrect
This charity was set up to gather money for the poor.
_________________________

HI , I WOULD LIKE TO KNOW WHY GATHER CAN'T BE CORRECT IN THIS SENTENCE

THANKS, : - )

[Torsten]

You can gather information but you collect money, that means you take payments from other people and organizations.

TOEFL listening lectures: A university lecture in the Social Sciences Department