If carbon emissions continue to rise at the current rate, by the year 2040 ozone density in the upper stratosphere will drop to a volume more than two-third lower than were those in 1930, according to scientific projections.

If carbon emissions continue to rise at the current rate, by the year 2040 ozone density in the upper stratosphere will drop to a volume more than two-third lower than were those in 1930, according to scientific projections.

A – will drop to a volume more than two-third lower than were those

B – will drop to a volume more than two-third lower than that

C – would drop to a volume more than two-third lower than it was

D – would drop to a volume more than two-third lower than those

E – would drop to a volume more than two-third lower than they were

Right Answer: B

Error Identification: 

Identifier	Fix
Underlined comparison words “lower than”	Comparison
Underlined incorrect comparison between singular “volume” and plural “those”	Comparison

Difficulty Level: Medium

Explanation:

In the sentence, singular ‘volume’ is incorrectly compared to ‘those’, which suggests a plural subject. The only logical antecedent to ‘those’ would be ‘ozone density’, which is logically not similar to the ‘volume’. To correct this comparison error, volume should be compared to volume.

A – Incorrectly compares singular ‘volume’ to plural ‘those’. Hence, eliminated.

B – Correctly compares ‘volume’ to ‘that’, referring to volume, and rectifies the error. This is the correct answer.

C – ‘Is was’ is incorrect. Hence, eliminated.

D – Incorrectly compares singular ‘volume’ to plural ‘those’. Hence, eliminated.

E – Incorrectly compares singular ‘volume’ to plural ‘they’. Hence, eliminated.