Question

which sentence states a central idea of paragraphs 17-20?
○ california almond farmers rotate their crops between almonds and grasslands in order to utilize rented bee colonies to pollinate their plants and almonds.
○ scientists at the usgs studied summertime land use in north dakota, south dakota, and minnesota to determine whether or not rented apiaries were beneficial to california almonds.
○ scientists have found that land converted from grasslands to row crops resulted in smaller and less profitable bee colonies, which in turn affected the almond crop in california.
○ the profitability of the beekeeping industry is a direct result of careful observation by local scientists, the results of which affect state and federal land - use laws and practices.

Explanation:

To determine the central idea of paragraphs 17 - 20, we analyze each option:

• The first option focuses on California almond farmers' crop rotation and bee colonies for pollination, but this may not be the central idea of the specified paragraphs.
• The second option is about USGS scientists studying land use in three states to see if rented apiaries benefit California almonds. This seems more like a specific study detail rather than a central idea.
• The third option states that scientists found converting grasslands to row crops led to smaller, less profitable bee colonies, which in turn affected California's almond crop. This connects the land - use change, bee colony impact, and almond crop, which is likely the central idea as it shows a causal relationship relevant to the topic.
• The fourth option talks about the profitability of the beekeeping industry being a result of scientist observation and its effect on laws, which is not related to the main theme of the paragraphs (likely about land use, bees, and almonds).

Answer:

Scientists have found that land converted from grasslands to row crops resulted in smaller and less profitable bee colonies, which in turn affected the almond crop in California.