A scientist made three observations: (1) in the world's temperate zones, food is more plentiful in the ocean than it ...

liwenong28 on December 19, 2020

Hi!

This is an argument evaluation question. I actually broke it down wrote it out like this:

1) in the world's temperate zones, food is more plentiful in the ocean than it is in fresh water;

food in ocean > food in fresh water

(2) migratory fish in temperate zones generally mature in the ocean and spawn in fresh water; and

Temperate zones: mature in ocean, spawn in fresh water

(3) migratory fish need much nourishment as they mature but little or none during the part of their lives when they spawn.

More nourishment needed as they mature (i.e. need more food) > little or none food needed when they spawn

"On the basis of those observations, the scientist formulated the hypothesis that food availability is a determining factor in the migration of migratory fish."

On the basis of the above statement, you can get rid of (A), (C) and (D) because they are irrelevant to the hypothesis - does not refer to distribution/food.

Subsequently the scientist learned that in the tropics migratory fish generally mature in fresh water and spawn in the ocean.

So combining the premises from (1) and (3),

the fish behaves differently in the tropics compared to the temperate zones - they mature in fresh water instead of the ocean; spawn in ocean instead of in fresh water.

(E) is the correct answer because it will be useful to know as (E) states "whether in the tropics food is less plentiful in the ocean than in fresh water". Which will explain why the fish behaves differently in the tropics vs in temperate zones, as well as tackle the scientist's hypothesis that food availability is a determining factor in the migration of migratory fish.

I hope the above helps! :)