The discovery that Earth’s inner core rotates independently of and more quickly than
Earth’s outer layers is responsible for advancing studies of the flow of heat from the inner
through the outer planet and of the formation and periodic reversal in direction of Earth’s
magnetic field.
A. core rotates independently of and more quickly than Earth’s outer layers is
responsible for advancing studies of the flow of heat from the inner through the
outer planet and of the formation and periodic reversal in direction of Earth’s
magnetic field
B. core rotates independently of and more quickly than Earth’s outer layers is
responsible for advancing studies of how heat from the inner core flows through
the outer planet, and the formation and periodic reversal in direction of Earth’s
magnetic field
C. core rotates independently and more quickly than Earth’s outer layers are
responsible for advancing studies of how heat from the inner core flows through
the outer planet, and how Earth’s magnetic field forms and the periodic reversal
of its direction
D. core, rotating independently and more quickly than Earth’s outer layers, are
responsible for advancing studies of the flow of heat from the inner through the
outer planet, and the formation and periodic reversal in direction of Earth’s
magnetic field
E. core, rotating independently of and more quickly than Earth’s outer layers, is
responsible for advancing studies of the flow of heat from the inner through the
outer planet and of how Earth’s magnetic field forms and the periodic reversal of
its direction
Answer:
------------------------------------------------------------------------------------------------------------

I would pick answer choice B) .

What is OA ?

OA is A.

Nasty sentence.

Core is "The discovery is responsible for advancing studies of X and of Y."
or: "Subject, verb, prepositional phrase, idiom requiring parallelism"

A) clunky but no obvious errors; leave in for now
B) "responsible for advancing studies of HOW X and of Y" breaks parallelism
C) "The discovery ARE responsible for" subject verb mismatch
D) "The discovery ARE responsible for" subject verb mismatch
E) "responsible for advancing studies of X and of HOW Y" breaks parallelism

There are other things wrong with several of the above, but those are the big things.