I do not think, "it" has a "referrent" issue here.
B and E seem to be changing the meaning.
C is wrong because of "in dealing".
D changes the meaning with the use of "capability".
Hence, I will go with A.
agree with you.. silly mistake.. E changes the meaning.
Would like to add some more notes (from my pervious post).
A looks good.
capability vs ability
Bush is capable of doing X -- means, he has the potential of doing X.
Bush is not able to do X -- means, (here we are not talking about capability. He might be having capablity and he can't do because of other circumstances.)
diminish RS's ability is correct
diminish RS's capability -- incorrect
Specially vs Especially
Specially means "particularly, in a disintguishing manner, or for a particular purpose."
Especially means "exceptionally, in a noteworthy manner, or particularly."
Example: This program has specially designed macros for word processors.
(A distinctive purpose)
Example: He did especially well in All-Star Game.
(A noteworthy performance) http://englishplus.com/grammar/00000287.htmIn
In this question, we can't eliminate with specially vs especially (correct me if I am wrong)
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