Why did Amir refused to help Hassan when he was bullied and raped by Assef?

A、
A、becauseAmirhatedHassanverymuch.;
B、
B、becauseHassandidnotneedhishelp.;
C、
C、becauseAmiristoofrightenedtohelpHassan.;
D、
D、becauseAmirknewHassanwashishalf-brotherwhowouldgrabBaBa’sloveforhim.