Find the following values for $f(x)=-3.($a$)f(8)($b$)f(-4)($c$)f(6\mathrm{.}5)($d$)f(-2\mathrm{.}5)($a$)$ Select the correct choice below and, if necessary, fill in the answer box to complete your choice. A$.f(8)=$ B$.f(8)$ is undefined. $($b$)$ Select the correct choice below and, if necessary, fill in the answer box to complete your choice. A$.f(-4)=$ B$.f(-4)$ is undefined. $($c$)$ Select the correct choice below and, if necessary, fill in the answer box to complete your choice. A$.f(6\mathrm{.}5)=$