I believe the answer is:
D) The bill required a 50-percent oath of loyalty from citizens in a reconstructed state.
In return of the oath, The states were required to give the black citizens with the right to vote. Lincoln perceive that 50-percent was a very radical number, and beleive that 10% is a farm more rational number. Since at that time Lincoln felt that he cannot obtain enough support, he choose to pocket veto it by taking no action to the bill.