Read each paragraph and then choose the letter of the main idea

Question

In calculating report card grades, teachers do not evaluate students based on a single test or
sample of performance. Combining several trustworthy scores from several different tests will
increase the reliability substantially. Teachers base grades on points accumulated1
from a variety
of sources. Therefore, the final grade is likely to be reliable even though a single test may not be.
From Sharon J. Sherman, Science and Science Teaching (Boston: Houghton Mifflin Co, 2000), 183.
Main Idea:

a. Teachers combine a variety of trustworthy scores in calculating reliable report
card grades.
b. Teachers often use a single major test as a reliable guide for calculating report
card grades.
c. There are many different methods teachers use to calculate report card grades.
d. When scores are accumulated from a variety of sources, teachers often discard
the highest and lowest scores.

Answer 1

a