During the time period from 1000 to 500 years ago, freshwater mussel populations declined precipitously in North America. It was during this same period that the rise of cultivation of corn and beans occurred in North America. It therefore seems possible that people living in North America at that time developed corn and bean cultivation to make up for the loss of the food source represented by mussels.
Determining which of the following would be most helpful in evaluation of the theory offered?
To answer the question, we must first identify "the theory offered." We see that it is the following:
It therefore seems possible that people living in North America at that time developed corn and bean cultivation to make up for the loss of the food source represented by mussels.
The passage also presents some support for the theory:
During the time period from 1000 to 500 years ago, freshwater mussel populations declined precipitously in North America. It was during this same period that the rise of cultivation of corn and beans occurred in North America.
We see that the reasoning of the argument is that, since the decline of mussel populations and the rise of cultivation of corn and beans occurred during the same time period, it may be that people developed corn and bean cultivation in response to the loss of the food source represented by the mussels.
To correctly answer this Evaluate question, we must find the choice such that, by determining what the choice mentions, one can weaken or strengthen the case for the theory.
(A) Whether in North America during the time period from 1000 to 500 years ago it was easier to cultivate corn and beans than to cultivate other crops
This choice is a little tricky to eliminate because it could seem that determining whether it was easier to cultivate corn and beans than to cultivate other crops would help with determining why people developed corn and bean cultivation 1000 to 500 years ago.
At the same time, this choice is incorrect because it helps in evaluating the case for the wrong theory. This choice helps with evaluating the case for the theory that people cultivated corn and beans rather than other crops because they were easier to cultivate than other crops.
We need to determine why people started cultivating corn and beans at all. After all, regardless of whether corn and beans are easier to cultivate than other crops, people may or may not have started cultivating them because of the decline in mussel populations.
Eliminate.
(B) Whether 1000 years ago North American mussel populations were as large as they had been in previous centuries.
The answer to this question wouldn't materially change what we know.
After all, regardless of how mussel populations of 1000 years ago compared with those of previous centuries, they still declined during the time period from 1000 to 500 years ago.
So, regardless of how mussel populations of 1000 years ago compared with those of previous centuries, people still may have begun cultivation of corn and beans in response to the decline in mussel populations.
Eliminate.
(C) Whether the process of cultivation of corn and beans has effects on bodies of water such that they become unsuitable as habitats for mussels
This choice is interesting.
After all, if the process of cultivation of corn and beans DOES have effects on bodies of water such that they become unsuitable as habitats for mussels, that information weakens the case for the theory. After all, in that case, it could be that what happened was not that cultivation of corn and beans was a response to the decline in mussel populations but rather that mussel populations declined because of effects of corn and bean cultivation on bodies of water inhabited by mussels.
So, if the process of cultivation of corn and beans does have such effects, that information weakens the case for the theory by indicating that the theory may have the cause and effect reversed from what they actually were.
On the other hand, if the process of cultivation of corn and beans does NOT have such effects, then that information strengthens the case for the theory by serving to rule out the possibility that the cause and effect are the reverse of how the theory has them.
Keep.
(D) Whether the people living in North America 1000 years ago were aware that corn and beans eaten together are significantly more nutritious than either of the two eaten alone
Determining this would not help with evaluating the case for the theory.
After all, regardless of whether people were aware that corn and beans eaten together are significantly more nutritious than either of the two eaten alone, they still may or may not have cultivated them in response to the decline in mussel populations.
Eliminate.
(E) Whether during the time period from 1000 to 500 years ago there were living in the bodies of fresh water in North America organisms other than mussels that people living there could have eaten
This choice is tricky to eliminate because it seems to bring up another way in which people could have made up for the loss of the food source represented by the mussel populations. Maybe they could have eaten something else that lived in bodies of fresh water.
Here's the thing though. Regardless of what else was available, when the mussel populations declined, there was a loss of a food source. So, even if there was another freshwater food source, people may have cultivated corn and beans in response to the decline in mussel populations. Sure, they may have still had another freshwater food source, but with the mussels gone, they may have sought to make up for that loss.
Eliminate.
Correct answer: C