Find the critical numbers of the function $\displaystyle {f{{\left({x}\right)}}}=-{3}{x}^{{5}}-{15}{x}^{{4}}+{20}{x}^{{3}}-{2}$ and classify them.

x = is a Select an answer Local Max Local Min Neither a max or min
x = is a Select an answer Local Max Local Min Neither a max or min
x = is a Select an answer Local Max Local Min Neither a max or min