This appears to be a question that tests one's ability to read with detail, I daresay. Is oil an ingredient or used to heat the other ingredients?
The basic ingredients from which cement is made are both cheap and plentiful. Materials as common as limestone and clay will do. Nevertheless, the price of cement is influenced by the price of oil, because turning the basic ingredients into cement in high-temperature kilns uses large amounts of energy.
Which one of the following can be logically inferred from the passage?
(A) Oil is one of the basic ingredients that make up cement.
Nope. Oil is used as a heat source.
(B) Oil is a source of energy for some of the kilns used in the making of cement.
Sounds good.
(C) The higher the price of cement rises, the higher the price of clay rises.
Back to front if anything. Clay is an ingredient of Cement. So what affects clay affects Cement. Not the other way around (at least on the GMAT, I daresay).
(D) Whenever oil prices rise, cement prices drop.
There is a correlation between OIL and CEMENT, but it is positive not negative. Eliminate.
(E) A given amount of cement costs no more than the total cost of its basic ingredients.
Freebie elimination. Generally, the cost of running machines is clearly factored into the price of a mass produced product.
Some Kudos would be nice! Trying to reach the next level!