What Is Singer's Rebuttal of the Argument That One Should

What is Singer's rebuttal of the argument that one should have no obligation to give more than five pounds to the Bengal Relief Fund because if everyone donated five pounds, then the needs of all the refugees would be met?

A) Singer argues that one is obligated to give more than other people in the same circumstances because one should strive to be more moral than one's peers.
B) Singer argues that this argument is based on a false hypothetical premise since not everyone will give five pounds, and so one has an obligation to give more than five pounds.
C) Singer argues that one has no obligation to give more than five pounds because one only has a duty to help others and be charitable to a minimal extent.
D) Singer argues that one should have obligations not only to give money to the Bengal Relief Fund but also to join a nonprofit organization working to help the needs of refugees.