Question

read the passage.
from hydroelectric power: how it works
so just how do we get electricity from water? actually, hydroelectric and coal - fired power plants produce electricity in a similar way. in both cases a power source is used to turn a propeller - like piece called a turbine, which then turns a metal shaft in an electric generator, which is the motor that produces electricity. a coal - fired power plant uses steam to turn the turbine blades; whereas a hydroelectric plant uses falling water to turn the turbine. the results are the same.
(from hydroelectric power: how it works by u.s. geological survey)
based on the information in the passage, which statement is true about both water and coal?

1. both can be used at the same electric power plants.
2. both are able to generate the same amount of electricity.
3. both can produce the power needed to generate electricity.
4. both are the main power sources used at electric power plants.

Explanation:

• For option 1: The passage says hydroelectric plants use water and coal - fired plants use coal, so they aren't used at the same plants. Eliminate 1.
• For option 2: The passage doesn't mention the amount of electricity each generates, so we can't say they generate the same amount. Eliminate 2.
• For option 3: The passage states that in hydroelectric plants, falling water turns the turbine (providing power to generate electricity), and in coal - fired plants, coal is used to create steam that turns the turbine (so coal provides the power to generate electricity). So both can produce the power needed to generate electricity.
• For option 4: The passage doesn't state that both are the main power sources, and there are other power sources too (like solar, wind), so we can't conclude this. Eliminate 4.

Answer:

1. Both can produce the power needed to generate electricity.