Hi,
I received a Pm to respond to this one.
A recent review of pay scales indicates
that CEOs now earn an average of 419 times more pay than blue-collar workers, compared to a ratio of 42 times in 1990.

According to a recent review, CEOs now earn an average of 419 times more pay than blue-collar workers. The ratio of the same was 42:1 in 1990.

Now let’s look at error of this sentence:
1. Usage of “a ratio of” is incorrect here. It’s ambiguous what does it refer to. Also, it breaks the parallelism between “419 times” and “42 times”. Only the expression “42 times” would have been enough to present the correct comparison.
PoE:a. that CEOs now earn an average of 419 times more pay than blue-collar workers, compared to a ratio of 42 times:
Incorrect for the reason stated above.
b. that, on average, CEOs now earn 419 times the pay of blue-collar workers, a ratio that compares to 42 times:
Incorrect. This choice suggests the ratio compares to 42 times, that is in 42 different times in 1990. This is illogical comparison.
c. that, on average, CEOs now earn 419 times the pay of blue-collar workers, as compared to 42 times their pay, the ratio:
Correct. The parallelism is correctly maintained. “a ratio” correctly modifies “ “42 times their pay”.
d. CEOs who now earn on average 419 times more pay than blue-collar workers, as compared to 42 times their pay, the ratio:
Incorrect. Per this choice, recent reviews indicate “CEOs”.
e. CEOs now earning an average of 419 times the pay of blue-collar workers, compared to the ratio of 42 times:
Incorrect. 1. Repeats the same error as in choice A.
2. Repeats the same error as in choice D.
Hope this helps.

Thanks.
Shraddha