$5\mathrm{.}1.$ What are these sets? Write them explicitly, listing their members. $($a$)\{\{2,4,6\}\{6,4\}\}\{4,6,8\}($b$)$ P$(\{7,8,9\})$ P$(\{7,9\})($c$)$ P$()($d$)\{1,3,5\}\{0\}($e$)\{2,4,6\}($f$)$ P$(\{0\})$ P$(\{1\})($g$)$ P$($P$(\{2\}))$