Differentiate y = csc(x)cot(x).
a. y'= -csc(x)[csc²(x) + cot²(x)]
b. y'= -csc(x) [csc²(x) - cot²(x)]
c. y'= -csc(x)[csc(x) + cot(x)]
d. y' = csc³(x) cot(x)