【正确答案】A: Many synthetic elastomers have high hysteresis. This means that it would undergo deterioration rapidly due to great heat generated by constant flexing of automobile tires if a tire were made wholly these elastomers. In contrast, NR converts the stressing into elasticity and quickly rebounds with less heating. In addition, the high hysteresis of synthetic rubbers has an advantage in preventing slippage on wet surfaces and providing better abrasion resistance than NR. Thus, synthetic rubbers are suitable for the tread of tires while NR is appropriate for the sidewalls.