Q24

We know nothing about "immune-cell activity in mammals." We merely know that the extracts made by MUSHROOMS prevent tumors not by killing cancer cells directly, but by increasing immune-cell activity. What immune cell activity does in a mammal is not discussed in the passage. Therefore, we cannot state that answer choice (D) must be true. Hope that helps! Please let us know if you have any other questions.

Why isn't the answer A? Why is the answer C?

A says no benefit at all from eating wood, but the passage just says can't make glucose, there may be many benefits of eating wood other than glucose, like fiber content.

@Deke, Keep up the hard work and active participation in the threads! @djayasinghe, Happy to help. Let's look at (A) and (C). (A) says, "Mammals obtain no beneficial health effects from eating cellulose." We know from the stimulus that mammals cannot digest cellulose, but this does not mean that the mammals do not get health benefits from consuming it. It's possible that cellulose could aid in cleaning out the digestive tract or do some other beneficial function. Thus, (A) is out. (C) says, "The greater the degree of branching of beta-glucans, the greater the degree of immune-cell activity it triggers in mammals." The stimulus told us that more branching means more anti-tumor activity. Additionally, we now that beta-glucan's anti-tumor mechanisms involve the stimulation of immune cell activity. Thus, it's likely that more branching means more immune-cell activity. This is why (C) is the correct answer choice. Does this make sense? Let us know if you have any other questions!