We have an option to buy & sell stock on NSE & BSE.

But if I want to trade An weekly option I don’t see any option to buy it on NSE OR BSE Platform

Why this is so / not available to trade a option BSE OR NSE?

Ideally if I want to trade An option on BSE I can’t trade it by default it is traded on NSE platform.

Is there any other way to trade An option on BSE?

BSE only allows Options and FUT trading for Sensex. They do not allow derivatives (options and future) trading for stocks.