Species I: p-methoxybenzyl carbocation

Here are the resonance structures for each species and an explanation of their stability:

Species I: $p$-methoxybenzyl carbocation

The methoxy group ($-\text{OCH}_3$) is an electron-donating group by resonance (+R effect). It is located at the para position relative to the benzylic carbon.

1. Initial structure: Positive charge on the benzylic carbon. $$\begin{array}{c} \text{CH}_2^+ \\ | \\ \text{C}_6\text{H}_4 \\ | \\ \text{OCH}_3 \end{array}$$ (The positive charge is on the