The United States petroleum industry’s cost to meet environmental regulations is projected at ten percent of the price per barrel of refined petroleum by the end of the decade.Option Elimination -
There are two things to avoid on GMAT (I know it's easier than done, but it'll surely help; conversely, not avoiding these two will do their best to ensure that you get into the trap). Our goal is to avoid the traps and not get into them and lose marks; back to our two things.
1. Using your ear - You are wrong if your ear said that one of the two "cost to" or "cost" is better. Both are ok. "Cost of" indicates the value of an item or a service. E.g., The cost of the car is $30,000. "Cost to" expresses the amount required to perform an action. E.g., The cost to repair the car was substantial.
2. Using Idioms - If you think Estimated to be is correct and Estimated at is wrong, then you are wrong. Both are ok. "Estimated at" is used to provide a specific numeric estimation. E.g., The cost of the project is estimated at $1 million. "Estimated to be" is used when expressing general estimation or approximation. E.g., The number of attendees is estimated to be around 500.
So, it's difficult for most of us, but the earlier we stop these 2, the quicker we'll reach your goal of getting a better scope. Oh, you think you know idioms very well and are all good. Here is the googly for you:
https://gmatclub.com/forum/gone-are-the ... 65017.htmlAgainst these two, look for "the meaning" that, if difficult at first, will never let you down. The easier path is normally the difficult path in the end.

Anyway, enough of philosophy and gyan, returning to our elimination here. Before that, let's simplify this "ten percent of the price per barrel of refined petroleum" to clarify things. Let's assume the price per barrel of refined petroleum is $70. So what is 10% of $70? It's $7. So ultimately, all this "ten percent of the price per barrel of refined petroleum" translates to $7, which is some number.
(A) The United States petroleum industry’s cost to meet environmental regulations is projected at ten percent of the price per barrel of refined petroleum by the end of the decade. - We are projecting something by the end of the decade, a time marker. So the skeleton of the sentence is "cost is projected at $7 by the end of the decade." We are projecting something for ten years later. So, will this not be a better way of saying, "It is estimated that by the end of the decade, the cost will be $7." Using the future rather than the present tense for the future is better. "Projected at" refers to a specific location, not a projected value. E.g., The company's new headquarters is projected at the city center. "Projected that" is typically used to provide additional information and not express future projections. E.g., The report projected that the company's profits would increase by 20% this year. Thus, I used "Estimated."
(B) The United States petroleum industry’s cost by the end of the decade to meet environmental regulations is estimated at ten percent of the price per barrel of refined petroleum. Though it is better than A, using the future tense to refer to the future is better than using the present tense for the future.
(C) By the end of the decade, the United States petroleum industry’s cost of meeting environmental regulations is projected at ten percent of the price per barrel of refined petroleum. - same issue as in A and B.
(D) To meet environmental regulations, the cost to the United States petroleum industry is estimated at ten percent of the price per barrel of refined petroleum by the end of the decade. It's the same tense issue.
(E) It is estimated that by the end of the decade the cost to the United States petroleum industry of meeting environmental regulations will be ten percent of the price per barrel of refined petroleum. Best amongst the lot. "It is estimated that by the end of the decade, the cost will be $7."