The correct answer is (C) with.
The employees demanded pay parity with their counterparts in the Central Government. This means that they wanted to be paid the same amount as their colleagues who work for the Central Government.
The other options are not correct because they do not convey the meaning of pay parity.
(A) towards means “in the direction of.” This does not make sense in the context of the sentence.
(B) as means “in the same way as.” This is not correct because the employees are not demanding to be paid in the same way as their counterparts in the Central Government. They are demanding to be paid the same amount.
(D) like means “similar to.” This is also not correct because the employees are not demanding to be paid a similar amount to their counterparts in the Central Government. They are demanding to be paid the same amount.