Tay-Sachs disease is caused by a deficiency of __________ which results in an accumulation of ___________.

A)sphingomyelinase;sphingomyelin
B)ceramidase;ceramide
C) $\alpha$ -galactosidase A;GM₁ ganglioside
D)lysosomal N-acetylhexosaminidase A;GM₂ ganglioside
E) $\beta$ -glucosidase;glucosylceramide