Deborah Aguiar-Velez, founder of sistemas corporation, has written a computer textbook in Spanish for people who speak Spanish and so then do not have to rely on translations from English.

A. for people who speak Spanish and so then
B. for people who speak Spanish, and then they
C. for people speaking Spanish who
D. so that people who speak Spanish
E. so that people can speak Spanish and then.

OA C, but i feel that answer should be D

Can someone please justify that why the answer is C