6. Adult female rats who have never before encountered rat pups will start to show maternal behaviors after being confined with a pup for about seven days. This period can be considerably shortened by disabling the female’s sense of smell or by removing the scent-producing glands of the pup.Which of the following hypotheses best explains the contrast described above?
(A) The sense of smell in adult female rats is more acute than that in rat pups.
(B) The amount of scent produced by rat pups increases when they are in the presence of a female rat that did not bear them.
(C) Female rats that have given birth are more affected by olfactory cues than are female rats that have never given birth.
(D) A female rat that has given birth shows maternal behavior toward rat pups that she did not bear more quickly than does a female rat that has never given birth.（E）
(E) The development of a female rat’s maternal interest in a rat pup that she did not bear is inhibited by the odor of the pup.
7. The interview is an essential part of a successful hiring program because, with it, job applicants who have personalities that are unsuited to the requirements of the job will be eliminated from consideration.The argument above logically depends on which of the following assumptions?
(A) A hiring program will be successful if it includes interviews.
(B) The interview is a more important part of a successful hiring program than is the development of a job description.
(C) Interviewers can accurately identify applicants whose personalities are unsuited to the requirements of the job.
(D) The only purpose of an interview is to evaluate whether job applicants’ personalities are suited to the requirements of the job.（C）
(E) The fit of job applicants’ personalities to the requirements of the job was once the most important factor in making hiring decisions.
8. An overly centralized economy, not the changes in the climate, is responsible for the poor agricultural production in Country X since its new government came to power. Neighboring Country Y has experienced the same climatic conditions, but while agricultural production has been falling in Country X, it has been rising in Country Y.Which of the following, if true, would most weaken the argument above?
(A) Industrial production also is declining in Country X.
(B) Whereas Country Y is landlocked, Country X has a major seaport.
(C) Both Country X and Country Y have been experiencing drought conditions.
(D) The crops that have always been grown in Country X are different from those that have always been grown in Country Y.（D）
(E) Country X’s new government instituted a centralized economy with the intention of ensuring an equitable distribution of goods.
9. Useful protein drugs, such as insulin, must still be administered by the cumbersome procedure of injection under the skin. If proteins are taken orally, they are digested and cannot reach their target cells. Certain nonprotein drugs, however, contain chemical bonds that are not broken down by the digestive system. They can, thus, be taken orally.The statements above most strongly support a claim that a research procedure that successfully accomplishes which of the following would be beneficial to users of protein drugs?
(A) Coating insulin with compounds that are broken down by target cells, but whose chemical bonds are resistant to digestion
(B) Converting into protein compounds, by procedures that work in the laboratory, the nonprotein drugs that resist digestion
(C) Removing permanently from the digestive system any substances that digest proteins
(D) Determining, in a systematic way, what enzymes and bacteria are present in the normal digestive system and whether they tend to be broken down within the body（A）
(E) Determining the amount of time each nonprotein drug takes to reach its target cells
