The correct answer is: D. Neither I nor II follows
The statement “A neurotic is a non-stupid person who behaves stupidly” does not provide enough information to support either conclusion I or II.
Conclusion I states that “Neuroticism and stupidity go hand in hand.” This conclusion is not supported by the statement, because the statement does not say anything about whether or not all neurotic people are stupid. It is possible that some neurotic people are intelligent, and some are not.
Conclusion II states that “Normal persons behave intelligently.” This conclusion is also not supported by the statement, because the statement does not say anything about whether or not all normal people behave intelligently. It is possible that some normal people behave intelligently, and some do not.
Therefore, neither conclusion I nor II follows from the statement.