1) At what value(s) of x, if any, would the value of the derivative be equal to zero?

A) When x=c and x=e only.

B) When x=b only.

C) When x=a, x=b, x=c, and x=d.

D) When x=a, x=b, and x=d.

Here, I put C.

2) At what value(s) of x would the derivative not exist?

A) When x=c and x=e only.

B) When x=c only.

C) When x=a, x=b, x=d, and x=e only.

D) When x=a, x=b, and x=d only.

Here, I put A.

Am I right on these?