President Joseph R$.$ Biden's cabinet consisted of the Secretaries of Agriculture, Commerce, Defense, Education, Energy, Health and Human Services, Homeland Security, Housing and Urban Development, Interior, Labor, State, Transportation, Treasury, Veterans Affairs, and the Attorney General. Assuming that President Biden had $20$ candidates, including Dr$.$ Janet Yellen, to fill these posts $($and wished to assign no one to more than one post$),$ complete the following sentences.$($a$)$ The sample space is the set of all lists ofpeople chosen from$($b$)$The event that Dr$.$ Janet Yellen is the Secretary of the Treasury is the set of all lists of $15$ people chosen from position., in which Dr$.$ Janet Yellen occupies the$-$Select$-$ v $($Secretary of the Treasury$)$