The risk-return indifference curves for a risk-neutral investor are:

A) vertical lines.
B) straight lines with slope equal to one.
C) horizontal lines.
D) upward sloping lines that are bowed downward.

Risk-neutral investors have no preference for higher returns or lower risk, they only care about the absolute level of return. Therefore, their risk-return indifference curves are horizontal lines, indicating that they are indifferent to changes in risk as long as the return stays constant.