GMAT Sentence Correction (SC) | Re: Winship estimates that the three largest carriers - Delta, United

Winship estimates that the three largest carriers - Delta, United, and American -eachgenerate roughly $1billion annually from the sale of frequent-flier miles to hotels, rental-car companies, and others offering points-for-miles to their customers

A)generate roughly $1 billion annually from the sale of frequent-flier miles to
B)generates roughly $1 billion annually from the sale of frequent-flier miles to
C)from the sale of frequent-flier miles generates roughly $1 billion annually per year,
D)from