1. Key idea: bromination of aniline

Aniline is strongly activating due to the lone pair on nitrogen. In bromination, substitution occurs mainly at the ortho and para positions.

So, the arenium ion (Wheland intermediate) formed must come from attack of $Br^+$ at:

• ortho position, or
• para position.

A meta-substituted arenium ion is not involved in normal bromination of aniline.

2. Why ortho/para are favored

The amino group $(-NH_2)$ donates electron density to the ring by resonance:

Because of this resonance donation, the ring becomes electron-rich at the ortho and para positions. Hence electrophilic substitution occurs there.

Also, the corresponding arenium ion gets extra stabilization because the positive charge can be delocalized and one resonance form places the charge adjacent to nitrogen, allowing stabilization by lone-pair donation.

3. Which arenium ion is not involved?

Since bromination of aniline proceeds through ortho/para attack, the arenium ion corresponding to meta attack is not part of the mechanism.

Thus, among the given structures, the correct option must be the one representing the meta arenium ion.

The stored correct answer says this is Option D.

4. Final conclusion

The arenium ion not involved in bromination of aniline is the meta-complex, i.e. Option D.