Read the passage about taste sensitivity to phenylthiocarbonide (PTC) in humans and primates and choose the inference that can be correctly drawn from it.

Introduction / Context:
This question is based on a scientific passage describing how humans and non human primates vary in their ability to taste an artificial chemical called phenylthiocarbonide, or PTC. The passage explains that in most human populations a majority of people can taste PTC, and that this ability shows a long evolutionary history. You must choose the inference that best follows from these observations.

Given Data / Assumptions:

• A majority of individuals in nearly all human populations can taste PTC.
• The percentage of tasters varies, from about 60 percent in India to about 95 percent in Africa.
• A similar polymorphism (variation) is observed in non human primates.
• This polymorphism may reflect evolutionary selection for detecting other bitter, possibly toxic, substances.

Concept / Approach:
The central information is that most humans can taste PTC, which implies that only a minority cannot taste it or have an uncertain response. When the options use the phrase "indeterminant taste profile", we can reasonably interpret that as referring to individuals who do not taste PTC in the usual way, that is, non tasters or atypical responders. A correct inference should be consistent with the numerical and qualitative information given, without adding new claims not suggested by the passage.

Step-by-Step Solution:
Step 1: Note that in all mentioned populations, the majority are tasters: 60 percent in one example and 95 percent in another. Step 2: This implies that non tasters make up at most 40 percent in India and only 5 percent in Africa, that is, always a minority. Step 3: Examine option A, which says humans show the same taste profile as primates. The passage only says the polymorphism is observed in primates, not that the specific percentages match, so this cannot be safely inferred. Step 4: Examine option B, which claims humans prefer substances that are naturally sweet. The passage does not mention sweetness or preference, so this is unsupported. Step 5: Examine option C, which states that only a minority of the human population have an indeterminant taste profile. This aligns with the data that most can taste PTC, leaving a minority whose taste response is different. Step 6: Examine option D, which says a majority have an indeterminant taste profile. This directly contradicts the passage, which clearly states a majority can taste PTC. Step 7: Conclude that option C fits the numerical patterns described and is the correct inference.

Verification / Alternative check:
You can check again by translating percentages into everyday language. If 60 to 95 percent of a population can taste PTC, then 5 to 40 percent cannot. It is accurate to say only a minority have a different or indeterminant taste response. The passage does not claim anything about identical taste profiles between humans and other primates, nor does it reference preferences for sweetness. Therefore, the only inference that combines the numerical majority with a reasonable description of the remaining group is that only a minority have an unusual or indeterminant taste profile.

Why Other Options Are Wrong:
Option A is wrong because the passage does not give enough data to say that humans and non human primates share the same taste profile; it only notes that both show variation. Option B introduces an idea about preference for sweet foods, which is never mentioned. Option D is the direct opposite of the data given, since it suggests that most humans have an indeterminant taste profile, whereas the passage clearly states that most can taste PTC. These options either go beyond or contradict the information in the passage.

Common Pitfalls:
In inference questions, students often select answers that sound scientific or that mention key terms like "primates" and "reality", even if they are not actually supported by the passage. Another common trap is overlooking exact numerical information, such as the statement that a majority can taste PTC. Always pay attention to words like "majority" and "minority", and check whether your chosen option respects these proportions. If an option reverses the majority and minority, it cannot be an acceptable inference.

Final Answer:
The correct inference from the passage is Only a minority of the human population have an indeterminant taste profile.