Stock A$\text{'}$s beta is $1\mathrm{.}5$ and Stock B$\text{'}$s beta is $0\mathrm{.}5.$ Which of the following statements must be true about thescrsecurities? $($Assume market equilibrium.$)$

a$.$ Stock A must be a more desirable addition to a portfolio than Stock B$.$

b$.$ The expected return on Stock A should be greater than that on Stock B$.$

c$.$ Stock B must be a more desirable addition to a portfolio than Stock A$.$

d$.$ When held in isolation, Stock A has greater risk than Stock B$.$

$2.$ The expected return on Stock B should be greater than that on Stock A$.$

ONLY ONE ANSWER CAN BE CORRECT