The male sage grouse has air sacs that when not inflated, lie hidden beneath the grouse’s neck feathers. During its spring courtship ritual, the male sage grouse inflates these air sacs and displays them to the female sage grouse. Some scientists hypothesize that this courtship ritual serves as a means for female sage grouse to select healthy mates.
Which one of the following, if true, most strongly supports the scientists’ hypothesis?
What is important to understand here is the question requirement. What does the examiner want me to do as a solver? Clearly, the examiner wants me to choose an answer option that will most strongly support the hypothesis of the scientists. And what is the hypothesis? Clearly, the portion that says 'this courtship ritual serves as a means for female sage grouse to select healthy mates' is the hypothesis or the conclusion of the scientists. Well, what exactly is the ritual then? It is stated before. That the male sage grouse inflates these air sacs and displays them to the female sage grouse is the actual ritual. So, what must the right answer be doing? It should be establishing a relationship between health and air sacs. In other words, the health of a male sage grouse can be determined by the condition of its air sacs. Now, let us eliminate the options that do not match with what we have with us.
(A) Some female sage grouse mate with unhealthy male sage grouse. -
OUT OF SCOPE. Does not establish the link between health and air sacs. Not worried about what SOME female sage grouse do.
ELIMINATE(B) When diseased male sage grouse were treated with antibiotics, they were not selected by female sage grouse during the courtship ritual. -
OUT OF SCOPE. Again, shown no link between health and air sacs. Not worried about treatment given to male sage grouse.
ELIMINATE(C) Some healthy male sages grouse do not inflate their air sacs as part of the courtship ritual. -
OUT OF SCOPE. Not worried about what SOME healthy male sage grouse do.
ELIMINATE(D) Male sage grouse are prone to parasitic infections that exhibit symptoms visible on the birds’ air sacs. -
SHOWS THE RELATION BETWEEN HEALTH AND AIR SACS, THEREBY SUPPORTING THE HYPOTHESIS. No reason to eliminate.
KEEP - If the air sacs exhibit symptoms of parasitic infections, female sage grouse will be able to identify the male sage grouse with the infections during the ritual.
Thus, the hypothesis that the courtship ritual serves as a means for female sage grouse to select healthy mates is strengthened. (E) The sage grouse is commonly afflicted with a strain of malaria that tends to change as the organism that causes it undergoes mutation. -
OUT OF SCOPE. Not worried about what the sage grouse is commonly affected by. What about the link between air sacs and health?
ELIMINATE