The opposite of an astute person is a
a. liar.
c. weakling.
b. dimwit.

The answer is: dimwit.

An astute person would be considered someone who can produce the right circumstances by his or her own means to achieve a desired and projected goal or objective. On the opposite side, one would find a dimwit, which is a person of a slow, deficient or short mental capacity or intelligence that would be an easy prey of circumstances, especially difficult ones.  

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