The correct answer is D. Rs 500.00.
The obligation to cover a call option is the amount of money that the seller of the call option must pay to the buyer of the call option if the option is exercised. In this case, the value of the stock is Rs 1000 and the current value of the portfolio is Rs 1500. This means that the seller of the call option would have to pay the buyer of the call option Rs 500 if the option is exercised.
Option A is incorrect because it is the total value of the portfolio, not the obligation to cover the call option.
Option B is incorrect because it is the value of the stock, not the obligation to cover the call option.
Option C is incorrect because it is the current value of the portfolio, not the obligation to cover the call option.