While global temperatures have risen sharply over the last century, they have only recently eclipsed the Medieval period, during which scientists theorize that a series of volcanic eruptions sent the earth into a period of historic warmth.
a)they have only recently eclipsed the Medieval period, during which scientists theorize that a
b)they have only recently eclipsed those of the Medieval period, during which scientists theorize that a
c)it has only recently eclipsed the Medieval period, during which, scientists theorize, a
d)it has only recently eclipsed that of the Medieval period, during which scientists theorize a
e)they have only recently eclipsed those of the Medieval period, during which, scientists theorize, a
mentors please help me with this?