A is not context-free as this requires string comparison and thus an LBA.
B is not context free as we cant design a PDA here. We can solve it easily by putting $m=0$ and we get $a^nb^nc^n$ which is a well known non CFL.
C is not context-free as checking for a power of $2$ is above the limits of a PDA.
D is context-free as we can Push n 0's, followed by m 1's. Now, when 0 comes, we start popping and continue when 1 comes (when 1 comes stack must pop 1 and not 0) also. We accept on stack being empty.
So, correct option is D.