Explanation

Among the three types of investors listed:

Banks typically have low risk tolerance because they need to maintain liquidity to meet deposit withdrawals and have regulatory capital requirements that limit their risk-taking.

Insurance companies have moderate risk tolerance - they need to match assets to liabilities (insurance claims) and have regulatory constraints, though they can take some investment risk.

Endowments typically have the highest risk tolerance because:

1. They have long-term investment horizons
2. They can tolerate short-term volatility in pursuit of higher long-term returns
3. They often follow the "endowment model" which includes significant allocations to alternative investments (private equity, hedge funds, real estate)
4. They have spending policies that smooth out returns over time
5. They don't have the same regulatory constraints or liquidity needs as banks and insurance companies

The correct answer is B. Endowments.