A seemingly sly criminal plots to murder a rival gang leader and "get away" with the crime by pleading insanity. After killing his rival, he waits for the police to arrest him and enters a plea of "not guilty by reason of insanity." His plan fails when he

Apart from the low probability of success when pleading insanity, why did this sly criminal's plan fail?
a) The insanity plea cannot be used in murder cases.
b) Without a prior record of psychological disorders it is unlikely his insanity plea will be successful.
c) The court could determine that he did not meet the criteria for mental retardation.
d) The lack of evidence of a biologically-caused psychological disorder negates the insanity plea.

B