How opening price of CE and PE option decided?

How is opening and closing price of CE/PE options determined?

It’s the first traded price on the exchanges. You should check out the options module on Varsity

As answered above opening price would be 1st traded price, there is no underlying logic behind it, it’s just where supply meet demand or vice-versa for 1st time of that day.
Closing price is weighted average of last 30 mins trading for that day.