Question

selective breeding

approximately ninety plant species provide about 90% of the world’s food. all major food crops, including corn, wheat, and soybeans, are becoming more and more genetically modified (gm) and ethanol less and less genetic variation. the crops we grow are drought - tolerant and able to withstand herbicide spraying. they are more resistant to insect pests. one wild relative of corn called tripsacum or zea diploperennis, is exceptionally disease - resistant and is the only perennial in the corn family. zea diploperennis grows on only one mountain in western mexico.

as scientists have developed more productive crop varieties, farmers have switched from growing many traditional varieties to some high - yield varieties, and the number of corn varieties being cultivated and farmed has dropped from hundreds to about 20 types. by selectively breeding corn we have also reduced improved corn varieties’ usefulness in successfully breeding corn we have also reduced...

a the corn gene pool
b people’s dietary choices
c animal and insect biodiversity
d the number of food chains relying on corn

Explanation:

The problem is about selective breeding and crop resistance, which falls under Biology (a subfield of Natural Science). The question likely relates to the impact of reduced genetic variation in crops (like corn) due to selective breeding. Among the options, "insect and weed biodiversity" (Option C) is affected because genetically uniform crops (from selective breeding) can reduce the variety of pests, weeds, and associated organisms, impacting biodiversity. Other options: A (corn gene pool) – while gene pool is related, the text emphasizes resistance to insects/weeds and biodiversity loss. B (people’s dietary choices) – not directly related to the crop’s genetic uniformity. D (food chains relying on corn) – the text focuses on crop traits, not food chain count. So C is the best fit.

Answer:

C. insect and weed biodiversity