Sentence Correction

In build-to-suit projects, developers design and construct buildings to meet the needs of a primary tenant, who pays the developer a marginal fee for design and construction work and agrees to buy the completed building or will occupy all or most of it in exchange for a favorable long-term lease.

A). will occupy all or most of it
B). will occupy all of it, or most of it,
C). to occupy all or most of it
D). occupy all of it, or most,
E). they will occupy all of it, or most,

Answer is C

What is wrong with D ?

Thanks & Regards
Vinni