a.. If they use different cash A/C (cash A/C A and cash A/C B), then #2.
I assume that if you have tow cash A/Cs, then you probably have two bank A/Cs. Than you need to withdraw $500 from bank A/C B and deposit into bank A/C A.
b.. If you use the same cash A/C, then use #1.
Just remember Bank/Cash accounts are very sensitive.