Answer:
d. beta did a better job of explaining the returns than standard deviation
Step-by-step explanation:
Beta measures the systemic risk associated with the particular investment, it do not compute the total risk associated, which is more logical.
Standard deviation computes the total risk associated.
Some risk is natural, like the risk of floods, natural calamities, earthquake, etc:
That risk shall not counted as for comparison as that is associated universally. Further, the risk associated with particular factors like bankruptcy of a company, or some legal case issue of a company are precisely described by beta coefficient.
Thus, beta provides better details about explaining the returns.