I would like to add one more point that optional papers are added to the those exams that are for particular fields like if there is a post of lecturer they will ask for the test of optional subjects as well according to the nature of job.

Previously PCS sometime had optionals as well but now the pattern has totally changed and PMS dont have any condition of this type.

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"When Allah leads you to the edge of the cliff, Trust Him Fully, only 1 of 2 things will happen either He will catch you when you fall or He will teach you how to fly"