Sentence Correction

Though some education experts claim that the low test scores of children in the city can be raised by hiring more teachers and an increase in the amount of funding for textbooks and other supplies, others insist that doing this cannot guarantee any improvement.

A.by hiring more teachers and an increase in the amount of funding for textbooks and other supplies, others insist that doing this

B. by hiring more teachers and increasing funding for textbooks and other supplies, others insist that doing so

C. by a hiring of more teachers and increasing the amount of funding for textbooks and other supplies, other insist that doing so

D. by hiring more teachers and increasing the amount of funding for textbooks and other supplies, others insist that doing this

E. by hiring more teachers and an increase in funding for textbooks and other supplies, others insist that doing so


I narrowed it down to B/D, is "doing this" an idiom?

kdn508 wrote:Though some education experts claim that the low test scores of children in the city can be raised by hiring more teachers and an increase in the amount of funding for textbooks and other supplies, others insist that doing this cannot guarantee any improvement.

A.by hiring more teachers and an increase in the amount of funding for textbooks and other supplies, others insist that doing this

B. by hiring more teachers and increasing funding for textbooks and other supplies, others insist that doing so

C. by a hiring of more teachers and increasing the amount of funding for textbooks and other supplies, other insist that doing so

D. by hiring more teachers and increasing the amount of funding for textbooks and other supplies, others insist that doing this

E. by hiring more teachers and an increase in funding for textbooks and other supplies, others insist that doing so


I narrowed it down to B/D, is "doing this" an idiom?

This has more to do with parallelism than with idiom.
Option B says "by hiring ... and increasing..." This is parallel
Option E says "by hiring ... and an increase" This is not parallel

Correct Option: B