Cassy reports a gross tax liability of $1,000. She also claims $400 of nonrefundable personal credits, $700 of refundable personal credits, and $200 of business credits. What is Cassy's tax refund or tax liability due after applying the credits?
A. $1,000 taxes payable
B. $0 refund or taxes payable
C. $700 refund
D. $300 refund
Answer: D. $300 refund