Answer:
A. The color was pungent and foul.
Step-by-step explanation:
Synesthesia is seen as a condition that implies sensing phenomenon through a sense that is not meant to be used in that situation, the most usual simulation of it is colored hearing - when a person sees a song or a voice as a color. So, basically, it is an occurrence of mixed senses.
In the given sentence, to get the synesthesia effect, we should replace too bright with pungent and foul. Too bright means that color is strong and overflowed with light. Adjectives pungent and foul are used when describing a smell or taste being strong, pervasive, intensive, and disgusting. Therefore, eyesight is here permeated with a sense of taste and smell, which forms synesthesia.