Which of the following carbocations is expected to be most stable?

What are free radicals,carbanions,and carbocations? How are they formed?

The decreasing order of stability of the following carbocations is:
$A$. $m-CH_3O-C_6H_4-CH_2^+$
$B$. $p-CH_3O-C_6H_4-CH_2^+$
$C$. $C_6H_5-CH_2^+$
$D$. $p-NO_2-C_6H_4-CH_2^+$

Among the following structures,which will show the most stable enamine formation?
(Where $Me$ is $-CH_{3}$)

In the following species, the one which is likely to be the intermediate during benzoin condensation of benzaldehyde is

Arrange the following free radicals in the correct order of their stability:
$(i)$ $CH_2=\dot{C}H$
$(ii)$ $\dot{C}H_3$
$(iii)$ $CH_3-\dot{C}H-CH_3$
$(iv)$ $(CH_3)_3\dot{C}$