Since 1981, when the farm depression began, the number of acres overseen by professional farm-management companies have grown from 48 million to nearly 59 million, an area that is about Colorado's size.
(A) have grown from 48 million to nearly 59 million, an area that is about Colorado's size
(B) have grown from 48 million to nearly 59 million, about the size of Colorado
(C) has grown from 48 million to nearly 59 million, an area about the size of Colorado
(D) has grown from 48 million up to nearly 59 million, an area about the size of Colorado's
(E) has grown from 48 million up to nearly 59 million, about Colorado's size
My answer : C
A,B : HAVE incorrect
E: about Colorado's size, what is colorado's size? not mentioned, incorrect
C and D are close. What I could eliminate was that "about the size of Colorado's" in the C. Its sort of repetion that you are already mentioning size of colorado, and using possessive noun to state the same. i tend to avoid possesive..
So, C

zaarathelab wrote:Since 1981, when the farm depression began, the number of acres overseen by professional farm-management companies have grown from 48 million to nearly 59 million, an area that is about Colorado's size.
(A) have grown from 48 million to nearly 59 million, an area that is about Colorado's size
(B) have grown from 48 million to nearly 59 million, about the size of Colorado
(C) has grown from 48 million to nearly 59 million, an area about the size of Colorado
(D) has grown from 48 million up to nearly 59 million, an area about the size of Colorado's
(E) has grown from 48 million up to nearly 59 million, about Colorado's size

[spoiler]I know why a,b and e are out, but don't know why D is wrong[/spoiler]

In A and B, have (plural) does not agree with the number (singular). Eliminate A and B.

In D and E, has grown...UP is either an error of redundancy or a change in meaning. To grow UP means to progress from childhood to adulthood. Whereas a child grows UP, the number of acres simply HAS GROWN. Eliminate D and E.

The correct answer is C.

zaarathelab wrote:Since 1981, when the farm depression began, the number of acres overseen by professional farm-management companies have grown from 48 million to nearly 59 million, an area that is about Colorado's size.
(A) have grown from 48 million to nearly 59 million, an area that is about Colorado's size
(B) have grown from 48 million to nearly 59 million, about the size of Colorado
(C) has grown from 48 million to nearly 59 million, an area about the size of Colorado
(D) has grown from 48 million up to nearly 59 million, an area about the size of Colorado's
(E) has grown from 48 million up to nearly 59 million, about Colorado's size

[spoiler]I know why a,b and e are out, but don't know why D is wrong[/spoiler]

D is out because of the use "the size of Colorado's" and the word "up" .. not needed.

Since 1981, when the farm depression began, the number of acres overseen by professional farm-management companies have grown from 48 million to nearly 59 million, an area that is about Colorado's size.
(A) have grown from 48 million to nearly 59 million, an area that is about Colorado's size
(B) have grown from 48 million to nearly 59 million, about the size of Colorado
(C) has grown from 48 million to nearly 59 million, an area about the size of Colorado
(D) has grown from 48 million up to nearly 59 million, an area about the size of Colorado's
(E) has grown from 48 million up to nearly 59 million, about Colorado's size

IMO:C

Another reason to eliminate D (IMO) is ellipis - redundancy. Size of Colorado's (Size).