Hedge funds are known for their lack of transparency. This is primarily because many hedge funds are reluctant to disclose information about their positions. The reason behind this reluctance is the fear that others may exploit this information to their advantage. This lack of transparency poses a significant challenge in risk measurement. Risk measurement is a critical aspect of managing hedge funds as it helps in understanding the potential losses that could occur due to adverse market movements. However, the lack of transparency makes it difficult to accurately measure the risk associated with hedge funds. Therefore, the statement made by the hedge fund manager is incorrect as hedge funds are not transparent and often refuse to reveal information about their positions.

Choice A is incorrect. While it is true that hedge funds can be heterogeneous, implying a variety of investment strategies and risk profiles, the assertion that they are transparent and disclose all information about their positions is not accurate. Hedge funds are known for their lack of transparency due to the proprietary nature of their trading strategies.

Choice B is incorrect. The statement contradicts the manager's claim about heterogeneity among hedge funds. Hedge funds are not usually homogenous; they employ a wide range of investment strategies and have varying degrees of risk tolerance, which contributes to their heterogeneity.