Discussion of greenhouse effects have usually had as a focus the possibility of Earth growing warmer and to what extent it might, but climatologists have indicated all along that precipitation, storminess, and temperature extremes are likely to have the greatest impact on people.
(A) Discussion of greenhouse effects have usually had as a focus the possibility of Earth growing warmer and to what extent it might,
(B) Discussion of greenhouse effects has usually had as its focus whether Earth would get warmer and what the extent would be,
(C) Discussion of greenhouse effects has usually focused on whether Earth would grow warmer and to what extent,
(D) The discussion of greenhouse effects have usually focused on the possibility of Earth getting warmer and to what extent it might,
(E) The discussion of greenhouse effects has usually focused on whether Earth would grow warmer and the extent that is,
found this question on the prep. The OA is C.
can someone tell me that why A,B,E are wrong in terms of parallelism, thank you!