Source: GMATPrep Test
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'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 millio, has reached
E) enrollment: students in public schools have grown steadily in number since the mid-1980's and, at nearly 47 millio, are at
I chose E, but the correct ans is D. Can the instructors walk through the different ans choices. What role does ":" play in C, D and E.
Thanks in advance.