Explanation:

- In September 2019, Sunil Arora took over the chairmanship of the Association of World Election Bodies (A-WEB) for the term 2019-21.

- Om Prakash Rawat: He was a former Chief Election Commissioner of India but was succeeded by Sunil Arora before A-WEB chairmanship.

- Sushil Chandra: He served as the Chief Election Commissioner after Sunil Arora's term ended.

- Ashok Lavasa: He was an Election Commissioner but not involved in A-WEB leadership.

The correct answer is:

- Option 4: Sunil Arora

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