Because of many young . . . . / That many young . . .

.......... many business executives fear this country will lose its economic preeminence.
A. As poorly educated and trained as many young recruits to the United States work force are
B. So poorly educated and trained are many young recruits to the United States work force that (Answer Key)
C. Because of many young recruits to the United States work force who are so poorly educated and trained
D. That many young recruits to the United States work force are so poorly educated and trained is why

Hi,
What's wrong with C and D? They look OK to me. What are their mistakes?

Thank you.