Explanation:

- Begin by numbering the Fridays: 1, 2, 3, 4, 5, and 6.

- Condition (i): The Clerk post must come before the Watchman post.

- Condition (ii): The Lecturer post cannot be second.

- Condition (iii): The PRO must be released after the Principal post.

- Condition (iv): Accountant post is on the fifth Friday, cannot follow PRO.

- Condition (v): Watchman can’t be released last.

Let's build the schedule step by step:

- Place the Accountant on the fifth Friday.

- Since Watchman cannot be last, place it on the fourth or earlier. But it must come after Clerk.

- This restricts the Clerk post to be at least one position earlier than Watchman.

- Principal and PRO must be on consecutive Fridays, with Principal first.

- Considering all conditions, a valid sequence is:

1. Principal

2. PRO

3. Clerk

4. Watchman

5. Accountant

6. Lecturer

- Therefore, the notification released after the PRO post is the Clerk.

Correct Answer: Option 3 – Clerk