The correct answer is B. Rs. 1,00,000.
The minimum rent is Rs. 1,00,000. This is the amount that Mr. Ashok must pay, regardless of the amount of production. The rate of royalty is Rs. 1 per ton. This means that Mr. Ashok will pay Rs. 80,000 in royalties for the 80,000 tonnes of production. However, the minimum rent is Rs. 1,00,000, which is more than the amount of royalties due. Therefore, Mr. Ashok must pay Rs. 1,00,000 in rent.
Option A is incorrect because it is the amount of royalties due, not the total amount to be paid. Option C is incorrect because it is the sum of the minimum rent and the royalties due, but the minimum rent is more than the royalties due. Option D is incorrect because it is the amount of production, not the total amount to be paid.