From the following sets $\{p_1,p_2\},$ select all that are linearly independent subsets of $P_3.$ There may be more than one correct answer.

A$.$ The polynomials $p_1(t)=1+t^2$ and $p_2(t)=1-t^2.$

B$.$ The polynomials $p_1(t)=2t+t^2$ and $p_2(t)=1+t.$

C$.$ The polynomials $p_1(t)=2t-4t^2$ and $p_2(t)=6t^2-3t.$

D$.$ None of the above.