The United States petroleum industr'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. (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. (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. (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. (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. (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.