Sentence Correction

Hello Mo2men,

A) they have only recently eclipsed the Medieval period, during which scientists theorize that a
-->illogical comparison-->temperatures eclipsed period.


during Medieval period, scientists theorize that a series of volcanic eruptions sent the earth into a period of historic warmth
-->illogical meaning/ contrary to the fact meaning since scientists didn't theorize during Medieval period; instead a series of volcanic eruptions sent the earth into a period of historic warmth during Medieval period.

-->Further,
during Medieval period, scientists theorize that a series of volcanic eruptions sent the earth into a period of historic warmth

during Medieval period is an inital modifier modifying verb theorize
Tense conflict: Simple present tense for an event(theorize) that occured in past.

B) they have only recently eclipsed the Medieval period, during Medieval period, scientists theorize that a series of volcanic eruptions sent the earth into a period of historic warmth.

-->comparison is fine, unlike that in A.
-->meaning/logic and tense errors, like those in A



C) it has only recently eclipsed the Medieval period, during which, scientists theorize, a
-->pronoun error: it cannot refer to temperatures.
-->illogical comparison, as is the case in A.

D) it has only recently eclipsed that of the Medieval period, during which scientists theorize a
-->pronoun error.
-->same logic/meaning and tense errors as were in A and B.

ans is E.

E. they have only recently eclipsed those of the Medieval period, during which, scientists theorize, a

-->Scientists theorize is a non essential modifier and thus we can get rid of it without changing intended meaning.

-->No tense conflict as was the case in A ( as well as in B and D ):
during Medieval period, a series of volcanic eruptions sent the earth into a period of historic warmth.

initial modifier during Medieval period modifying sent, which is not in simple present tense, unlike tense in A , which is simple present tense.