Cartilage is a tough tissue that contains a protein called collagen.
Sharks have a cartilage skeleton.
Sharks have a skeleton made of tough tissue that contains a protein called collagen.
What has skeleton made of tough tissue that contains a protein called collagen?

(a) mammals
(b) rocks
(c) animals
(d) sharks
(e) a fish
(f) cows
(g) humans
(h) plants