Thanks Superman,
I visited Zerodha Varsity site and found the below response from Nithin:
"You could maybe use this Code: 13010 – Financial intermediation/Investment activities. This seems be the closest category to investment/trading related activity."
This I think is his opinion, and the words "could maybe" do not sound convincing, still I know he is best placed to give this "suggestion".
I request senior members, Smarttrade, Timepass, Canakhil among others to kindly reconfirm for benefit of all, since they themselves will be filing their returns putting the codes, so it will more authentic and convincing.