Which Is a Characteristic of Hagfishes

Which is a characteristic of hagfishes?

A) They have both a cranium and skeleton made of bone.
B) They have a cranium made of cartilage.
C) They have a cranium made of bone and vertebrae made of cartilage.
D) They have a cranium made of bone but lack vertebrae.
E) They have vertebrae made of cartilage but lack a cranium.