IMO ALarge corporations are often more successful than small companies at retaining employees with high potential and at providing opportunities for professional development.
A. Large corporations are often more successful than small companies at retaining employees
B. Larger corporations are often more successful at retaining employees than smaller companies
C. Large corporations, often more successful than small companies at retaining employees
D. A large corporation often more successfully retains employees than does a small company
E. Large corporations are often more successful as small companies at retaining employees
Placement is the key here.
after the underline part we have -->with high potential and it is modifying employees so in no case we can have smaller companies with high potential. For that reason lets eliminate
B and DLet tackle C now, I am looking at it and I don't see any verb here -->
C is gone . It is a fragment
Coming to E don't we need a than after more for the comparison. -- >
E is gone too.