When a highly electron-rich alkene such as the given 4-methoxystyrene derivative is brominated, trans- and cis-dibromide are produced in approximately equal amounts. Explain this observation.

A cyclic intermediate that can result in a racemic mixture of products is involved.

Bromonium ion intermediate can be formed from both faces of the alkene leading to the pair of enantiomers.

The reaction involves a bromonium ion intermediate through a concerted transition state forming both cis and trans dibromides.

The reaction involves a highly stable carbocation via a stepwise transition state forming both cis and trans dibromides.