Public relations personnel recruitment

The average grade of A is: (86×6+90×4)÷ 10=87.6 (points),

The average grade of B is: (92×6+83×4)÷ 10=88.4 (points),

The average grade of C is: (90×6+83×4)÷ 10=87.2 (points),

The average score of Ding is: (83×6+92×4)÷ 10=86.6 (points),

Because b has the highest average score,

So b will be accepted.

Therefore, choose: B.