Set 3: Inferences

Explanation

Answer: A

PASSAGE

Octopuses have three hearts. Two hearts pump blood to the gills, while the third pumps it to the rest of the body. Interestingly, the heart that delivers blood to the body stops beating when the octopus swims, which is why these animals prefer crawling—swimming exhausts them quickly.

What can be inferred about octopus locomotion?

A. They avoid crawling whenever possible.✓ Correct

B. Their cardiovascular system makes sustained swimming energetically costly.

C. Swimming is their most efficient form of movement.

D. They have only one functional heart.

Detailed Explanation

This question asks you to draw a logical conclusion from the text. When swimming, one heart stops—reducing blood flow. This makes swimming exhausting, implying crawling is more sustainable. A valid inference must be supported by evidence in the passage, even if not stated directly. Look for clues in the text that strongly suggest the answer. Avoid conclusions that require assumptions beyond what's written. Valid inferences are strongly supported by multiple pieces of evidence in the text. Be cautious of choices that go too far beyond what the passage actually states. The best inference is the one most directly supported by textual evidence.

Key Evidence:

• "heart stops beating when the octopus swims"

• "swimming exhausts them quickly"

Why others are wrong: A (They 'prefer crawling.'), C (Swimming is exhausting, not efficient.), D (They have three hearts; one just pauses.).