Each of two particular inspection systems that are based on different principles would detect all product flaws but would also erroneously reject three percent of flawless products.Assuming there is no overlap between the products erroneously rejected by the two systems and also no interference between the systems if both operate，using both systems and rejecting only those products found flawed by both would be a way of avoiding all erroneous rejections.
Which of the following most precisely characterizes the reasoning in the argument？
（A）The reasoning is conclusive，that is，the conclusion cannot be false if the statements offered in its support are true.
（B）The reasoning is strong but not conclusive，if the statements offered in support of the conclusion are true，they provide good grounds for that conclu-sion，though it is possible that additional infor-mation might weaken the argument.
（C）The reasoning is weak; the statements offered in support of the conclusion，though relevant to it，by themselves provide at best inadequate grounds for the conclusion.
（D）The reasoning is flawed in that the conclusion is no more than a paraphrase of one of the pieces of evidence offered in its support.
（E）The reasoning is flawed in that the argument treats evidence that a factor is necessary to bring about an event as if it were evidence that the factor is sufficient to bring about that event.
In recent years，there has been a dramatic decline in the population of the shrike，a predatory bird that inhabits flat land，such as farms and pastures.Some ornithologists hypothesize that this decline is due to the introduction of new，more effective pesticides to control the insect species on which shrikes prey.
The answer to which of the following questions is NOT relevant to evaluating the ornithologists‘ hypothesis？
（A）Was there a decline in the shrike population before the new pesticides were first used？
（B）Have shrike populations declined significantly in those habitats where the new pesticides have not been used？
（C）Have the new pesticides more significantly reduced the population of insect species on which shrikes prey than did the pesticides previously used？
（D）Are insects that have consumed the new pesti-cides more toxic to the shrikes that eat those insects than were insects that consumed the less effective pesticides？
（E）Are the new pesticides considered by most people to be less harmful to the environment than the old pesticides were considered to be？
Certain extremely harmful bacteria found only in sewage are difficult to detect directly.Testing for E.coli，an easily detected and less harmful type of bacteria，in ocean water would be a reliable way of determining whether or not these more harmful bac-teria are present，since ocean water contains E.Coli only if the water is contaminated with sewage that contains the harmful bacteria.
Which of the following，if true，most seriously weakens the argument？
（A）There are many different strains of the E.coli bacteria，and only some of these strains are harmful.
（B）Some types of bacteria found in sewage are neither disease-causing nor difficult to detect directly.
（C）Some of the types of bacteria found in sewage along with E.coli are not harmful to people unless the bacteria are ingested in large quantities.
（D）E.coli dies out much more quickly than some of the more harmful bacteria found in sewage and then can no longer be easily detected.
（E）Some of the types of bacteria found in sewage along with E.coli reproduce at a slower rate than E.coli