Passage Summary: Many different hormones can raise blood sugar, and this is probably because the brain is a picky eater that only uses glucose to survive.

Conclusion: The ability of various human hormones to increase blood glucose levels is likely explained by a specific metabolic requirement of the brain.

Reasoning: Unlike most other cells that can process fats and proteins, brain cells depend entirely on glucose and will die if levels become too low.

Analysis: In this 'Identify the Conclusion' task, we look for the claim that the rest of the passage is trying to prove. The first sentence introduces a fact, and the second sentence offers an explanation for that fact, signaled by the phrase 'The reason for this is probably.' The subsequent sentences provide the evidence regarding brain cell metabolism to support that explanation. Therefore, the second sentence is the primary point the author wants us to accept.