单选题 When a driver is suspected of having had too much to drink, testing the driver's ability to walk a straight line gives a more reliable indication of fitness to drive than does testing the driver's blood-alcohol level.
Which of the following, if true, best supports the claim made in the statement above?

A、 Not all observers will agree whether or not an individual has succeeded in walking a straight line.
B、 Because of genetic differences and variations in acquired tolerance to alcohol, some individuals suffer more serious motor impairment from a given high blood-alcohol level than do others.
C、 Tests designed to measure blood-alcohol levels are accurate, inexpensive, and easy to administer.
D、 More than half the drivers involved in fatal accidents have blood-alcohol levels that exceed the legal limit, whereas in less-serious accidents the proportion of legally intoxicated drivers is lower.
E、 (E) Some individuals with high blood-alcohol levels are capable of walking a straight line but are not capable of driving safely.

【正确答案】 B

【答案解析】[解析] 本题为支持题型，相对阅读难度较小，(B)说明由于基因的不同和对酒精的抵抗能力的差异，一些人在高血液酒精含量时所受的运动肌肉损伤要比另一些人多，而这些人在肌肉受损伤时走直路能力受到影响，所以支持了段落里的推理；(A)、(C)、(E)都起到反对作用，(D)无关。