The question contains four statements labeled as Statements I, II, III, and IV. You must determine which statement(s) is/are necessary to answer the question and select the appropriate option.

There are four tanks [P, Q, R, and S]. Each tank contains a different quantity of oil and water mixture. Find the difference between the total quantity of the mixture in tank P and tank R.

Statements:

I. The quantity of oil in tank P is 40 liters. The quantity of oil in tank Q is equal to the quantity of water in tank R. The ratio of oil and water in tank R is 5:6.

II. The ratio of oil and water in tank Q is 6:7. The quantity of water in tank P is equal to the quantity of oil in tank R.

III. The ratio of oil and water in tank P is 8:5. The quantity of water in tank P is equal to the quantity of oil in tank R.

IV. The total quantity of the mixture in tank S is 80 liters, which is 15 liters more than the total quantity of the mixture in tank Q.