Rewrite the following using mathematical symbols.

a$.P$ is equal to the set containing $t,n,c,$ and $d.$

b$.$ The set consisting of the elements $4$ and $7$ is a proper subset of $\{4,7,8,12\}.$

c$.$ The set consisting of the elements $0$ and $3$ is not a subset of $\{3,4,5,6\}.$

a$.P$ is equal to the set containing $t,n,c,$ and $d.$

$P=\{\}$

$($Use a comma to separate answers as needed.$)$

b$.$ The set consisting of the elements $4$ and $7$ is a proper subset of $\{4,7,8,12\}.$ Select the correct choice below and fill in the answer box to complete your choice. $($Use a comma to separate answers as needed.$)$

A$.$

B$.$

C$.$

D$.\{4,7,8,12\}in.$

E$.$

F$.\{4,7\}in.$

c$.$ The set consisting of the elements $0$ and $3$ is nota subset of $\{3,4,5,6\}.$ Select the correct choice below and fill in the answer box to complete your choice.

$($Use a comma to separate answers as needed.$)$