Explanation:

Let's break down each statement:

- He belonged to the Maukhari dynasty

- Incorrect. Harshavardhana belonged to the Pushyabhuti (or Vardhana) dynasty, not the Maukhari dynasty.

- He was defeated by Pulakesin II

- Correct. Harsha was defeated by Pulakesin II, the Chalukya ruler, on the banks of the Narmada.

- Ban, Mayura and Matanga Divakara were the famous writers at his court

- Correct. Banabhatta and others were noted scholars at Harsha’s court.

- Harsha himself wrote three plays - Ratnavali, Priyadarshika and Nagamanjari

- This is partially correct. Harsha definitely wrote Ratnavali and Priyadarshika, also Nagananda, not Nagamanjari.

Now, let's look at the options:

- Option 1: a, b and c (Includes incorrect statement 'a')

- Option 2: a, b and d (Includes incorrect statement 'a')

- Option 3: b, c and d (Best fits, except d should be Nagananda, not Nagamanjari)

- Option 4: a, c and d (Includes incorrect statement 'a')

Correct Answer:

Option 3: b, c and d