GMAT Sentence Correction (SC) | Re: Whereas a ramjet generally cannot achieve high speeds

Whereas a ramjet generally cannot achieve high speeds without the initial assistance of arocket, high speeds can be attained by scramjets, or supersonic combustion ramjets, in that they reduce airflow compression at the entrance of the engine and letting air pass through at supersonic speeds.

A) high speeds can be attained by scramjets, or supersonic combustion ramjets, in that they reduce

B) that high speeds can be attained by scramjets, or supersonic combustion ramjets, is a result of their