Which of the following statements is true?
1) Sharks have a skeleton made of bone, while ray-finned fishes have flexible skeletons made of cartilage.
2) Ray-finned fishes have a skeleton made of bone, while sharks have flexible skeletons made of cartilage.
3) Sharks have a series of rod-shaped bones in their muscular pectoral and pelvic fins, while lobe-fins have flexible skeletons made of cartilage.
4) Ray-finned fishes have a series of rod-shaped bones in their muscular pectoral and pelvic fins, while lobe-fins have flexible skeletons made of cartilage.
