Final answer:
The expected return on a zero beta portfolio would be equal to d. the risk-free rate.
Step-by-step explanation:
To construct a zero beta portfolio, you would need to invest in assets with a beta of zero. Beta measures the sensitivity of an asset's returns to the overall market. A zero beta asset would not be affected by market movements and would have no systematic risk. Since the expected return on a risk-free asset, such as a U.S. Treasury bill, is equivalent to the risk-free rate, the expected return on a zero beta portfolio would be equal to the risk-free rate.