A collection of logical operators is called functionally complete if every compound proposition is logically equivalent to a compound proposition involving only these logical operators. Hint: These are all $1-2$ sentence answers. If your justification goes beyond that, you$$re probably on the wrong track.

a$.$ Show that $,,$ and $$ form a functionally complete collection of logical operators.

b$.$ Show that $$ and $$ form a functionally complete collection of logical operators.

c$.$ Show that $$ and $$ form a functionally complete collection of logical operators.