GMAT Sentence Correction (SC) | Re: Astronomers at the Palomar Observatory have discovered a

Refer this question :
a-recent-study-on-lyme-disease-suggests-that-people-who-are-169777.html

A recent study on Lyme Disease suggests that people who are bitten by ticks, especially by the lone star tick, develop a severe allergy to meat that scientists believeto be turning into an epidemic
a.to be
b.would be
c.is
d.it is
e.it would be

and