max37274 wrote:Until about 400 million years ago. fishes-the first true swimmers-were jawless. Their feeding methods were limited to either sucking in surface plankton or sucking in food particles from bottom mud. With the development of biting jaws. however, the life of fishes changed dramatically, since jaws allowed them actively to pursue prey, to seize it in their jaws, and to manipulate it between their teeth. The jawed fishes then developed along two main lines one retained cartilage for its skeletons. for its skeletons, for example, sharks and rays: the other adopted bone as its principal skeletal material. From the latter group evolved the most abundant and diverse of all of today s vertebrate groups. the "teleosts" some 21,000 species, which vary from barracudas to sea horses

If all of the statements in the passage are true which one of the following must also the true?

(A) Fish are the primary prey of all jawed fishes
Incorrect : 'Primary' prey of fishes is not mentioned in the stimulus. Eliminated

(B) The jawless fishes did not prey upon other fish
Correct : The stimulus above states that the feeding methods of jawless fishes was limited to either sucking in surface plankton or sucking in food particles from bottom mud which implies that they did not prey upon other fish.

(C) Teleosts do not feed upon particles found in bottom mud
Correct : Oh well, the teleosts evolved from jawless fishes and the feeding method of jawless fishes was either sucking plankton or sucking particles found in bottom mud. Hence this is not true. Eliminated.

(D) Jawless fishes did not have cartilage as their skeletal material
Incorrect : It is stated in the passage above that out of the two groups one group of fishes RETAINED cartilage which means they did have cartilage. Eliminated.

(E) Jawless fishes became extinct approximately 400 million years ago
Incorrect : Nothing stated in the passage implies EXTINCTION. Eliminated.