Which statement is correct concerning agency relationships?

$($a$)$ A special agent is only authoried to perform a single act on behalf of the principal.

$($b$)$ The only party who can employ a broker as an agent to perform senices of real estate is the seller$/$owner$.$

$($c$)$ A sales associale is a general agent of the broken's principals.

$($d$)$ Afduclary relationship carnot be created without the payment of compensation.