20. Breakthrough that Earth's inner 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.
A. 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
B. 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
C. 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
D. 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
E. 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



I narrowed down the choices to B & C and thought C is concise because " of " is redundant as in B.

I know B maintains parallelism .But What's wrong with C?

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