Here the claim says that because small businesses employ more than big businesses, it is necessary to provide more incentives for them because they resorb the unemployment.
We have to look for an argument that undermine this statement.


(A) In general, people employed by small businesses report higher job satisfaction than do people employed by large businesses.
This strenghens our statement
(B) Among the currently unemployed are many people with sufficient job skills to perform the jobs that small businesses would create.
This one strenghens too.
(C) Providing an effective incentive for starting a business generally costs significantly less than providing an effective incentive for expanding a large business.
This strenghens the statement.
(D) A high proportion of small businesses fail within three years of starting because of their owners' inexperience.
(E) The average large business contributes more money to politicians’ campaign funds than the average small business does.
This statement strenghens.

So answer D.