Sentence Correction

Part of the proposed increase in state education spending is due to higher enrollment, since the number of students in public schools have grown steadily since the mid-1980's, and at nearly 47 million, are at a record high.

A) enrollment, since the number of students in public schools have grown steadily since the mid-1980's, and at nearly 47 million, are at
B) enrollment, with a number of students in public schools growing steadily since the mid-1980's and, at nearly 47 million, reaching
C) enrollment: since students in public schools have grown steadily in number since the mid-1980's and, at nearly 47 million, have reached
D) enrollment: the number of students in public schools has grown steadily since the mid-1980's and, at nearly 47 million, has reached
E) enrollment: students in public schools have grown steadily in number since the mid-1980's and, at nearly 47 million, are at

OA is D

A--agreement error between "the number" and "have grown"
B--says that students are growing, not the number of students
C--says "students in public schools...have reached a record high" when it should say the number has reached a record high
D--fixes A's agreement errorL "the number of students in public schools has grown steadily..."
E--says "students in public schools...are at a record high" when we know it's the number that is at a record high

IMO: D