Choose the letter of the sentence that best expresses the implied main idea of the following paragraph. 1. 1 A puddle of dark liquid under a car indicates a leak in the oil or transmission fluid. 2 Another warning sign of car trouble is uneven wear on tire treads. 3 If the outer edge of the tire tread wears out before the center, the tire is under-inflated. 4 The most significant early warning signal, however, is less and less mileage per gallon. 5 Lower fuel economy is caused by a variety of problems ranging from a clogged filter to ignition or carburetor trouble.