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

Nitro group ($-{\text{NO}}_2$) is strongly electron-withdrawing through both $-I$ and $-M$ effects. This destabilizes a nearby positive charge.In $p$ and $o$ positions, the $-M$ effect of $-{\text{NO}}_2$ acts directly on the carbocation center, severely destabilizing it.In the $m$ position, only the $-I$ effect acts (which is weaker with distance).However, comparing to an unsubstituted benzyl carbocation, any nitro group will destabilize the cation.Looking at the provided solution context (stability relative to each other when $-{\text{NO}}_2$ is present): The distance of the $-{\text{NO}}_2$ group matters for the $-I$ effect. The para-nitro isomer is often cited as more stable than ortho due to the distance from the cation. Note: Option A in standard keys often refers to the isomer where the withdrawal is least effective on the specific carbon. Actually, for benzyl systems, if there is a nitro group, meta is usually more stable than para/ortho because resonance withdrawal doesn't reach the benzylic carbon directly from the meta position.Wait, re-checking the source diagram: The question likely compares isomers. Para is usually the answer for "most stable" among nitro-substituted ones because the $-I$ effect is weakest at the furthest distance.