$k(x)=3x^{4}4x^3$

a$)$ What are the coordinates of the relative extrema? Select the correct choice below and, if necessary, fill in the answer box$($es$)$ to complete your choice.

$$ A$.$ The relative minimum point$($s$)$ islare $$ and the relative maximum point$($s$)$ is$/$are $.($Simplify your answers. Use integers of fractions for any numbers in the expression. Type an ordered pair. Use a comma to separate answers as needed$)$