How do economists define expected return and risk?

A$.$ Risk is the price of an asset a year from now, while expected return is the degree of uncertainty in the return a year from now.

B$.$ Expected return is the price of an asset a year from now, while risk is the degree of uncertainty in the return a year from now.

C$.$ Risk is the return expected on an asset during a future period, while expected return is the degree of uncertainty in the return on an asset.

D$.$ Expected return is the return expected on an asset during a future period, while risk is the degree of uncertainty in the return on an asset.