PT158 S3 Q20 ExplanationThe study of primates is interesting

Answer choices, explained

1. A

   Supported But Not Certain17% picked this

   The chimpanzee, a higher primate, evolved from

   The passage states that all higher primates evolved from a single diurnal lower primate species, but it never identifies that species as a lemur. The passage says some lemurs are diurnal lower primates, and higher primates evolved from a diurnal lower primate — but these could be different species of diurnal lower primates. The passage does not establish that the ancestral species was a lemur, let alone a chimpanzee's specific ancestor. Furthermore, "evolved from" describes a distant ancestral relationship, not a direct lineage claim linking chimpanzees specifically to lemurs. This inference requires assumptions beyond what the passage states.

   17%
2. B

   Correct61% picked this

   No primates indigenous to Madagascar are diurnal

   Why this is right

   The passage states that lemurs are the only primates indigenous to Madagascar (F3) and that lemurs are lower primates (F2). From these two facts, it follows necessarily that all primates indigenous to Madagascar are lower primates — and therefore no primates indigenous to Madagascar are higher primates. Since no higher primates are indigenous to Madagascar, no diurnal higher primates are indigenous to Madagascar either. This answer captures exactly this inference: "no primates indigenous to Madagascar are diurnal higher primates." The reasoning is airtight — if the entire set (higher primates) is excluded from Madagascar, then any subset of that set (diurnal higher primates) is also excluded. No additional assumptions are needed.

   Skill tested: Must be True · how this choice captures the argument's function is the move to repeat next time.

   61%
3. C

   Too Strong14% picked this

   No higher primate is

   The passage says all higher primates are thought to have evolved from a single diurnal species of lower primates. This tells us the ancestral species was diurnal, but it does not tell us that all current higher primates are diurnal. Evolution from a diurnal ancestor does not guarantee that all descendants remain diurnal. Many higher primate species could have evolved nocturnal habits over millions of years. In fact, some higher primates (like certain prosimians reclassified or owl monkeys) are nocturnal. The passage provides no information about the current activity patterns of higher primates as a group — only about their evolutionary origin.

   14%
4. D

   No Support6% picked this

   There are some lemurs without opposable

   The passage states that only primates have opposable thumbs — meaning ALL primates have them, and nothing else does. This means lemurs, as primates, have opposable thumbs. The passage does not say or imply that any lemurs lack opposable thumbs. The "only primates" formulation establishes that opposable thumbs are exclusive to primates, but it does not address variation within the primate order. Since lemurs are primates, the passage actually implies they DO have opposable thumbs, making this answer contradict the passage rather than follow from it.

   6%
5. E

   Too Strong3% picked this

   There are no nocturnal

   The passage says some species of lemurs are the only living lower primates that are diurnal. This means some lemur species are diurnal, but it does not say all lemurs are diurnal. The word "some" leaves open the possibility that other lemur species are nocturnal. In fact, many lemur species in the real world are nocturnal, and the passage's careful use of "some species of lemurs" rather than "all lemurs" signals that not every lemur is diurnal. This answer claims there are no nocturnal lemurs, which goes beyond — and likely contradicts — the passage's careful "some" qualifier.

   3%