The amount of short working is equal to:

Minimum rent + Royalty
Royalty - Minimum rent
Minimum rent - Royalty
Royalty - Amount paid to landlord

The correct answer is: C. Minimum rent – Royalty

The amount of short working is the difference between the minimum rent and the royalty. The minimum rent is the amount of rent that must be paid regardless of the amount of oil produced. The royalty is the amount of rent that is paid based on the amount of oil produced.

Option A is incorrect because the minimum rent is not added to the royalty.

Option B is incorrect because the royalty is not subtracted from the minimum rent.

Option D is incorrect because the amount paid to the landlord is not included in the calculation of the amount of short working.