How did Vincent enhance his physical appearance to resemble Jerome?

Vincent enhanced his physical appearance to resemble Jerome primarily by adopting Jerome's fashion style. This included wearing clothes and accessories that were typical of Jerome's image, which helped him to create a visual connection to his genetically superior counterpart. In the context of the film GATTACA, where appearance and genetic traits are heavily emphasized, this method of transformation was crucial for Vincent to blend in and fulfill his aspirations. By emulating Jerome's style, he aimed to present himself as someone who belonged to the elite class of genetically perfect individuals, despite not having the same inherent genetic advantages.

The other choices, while they may contribute to one's appearance in some contexts, do not play the same pivotal role in the film's narrative. For example, using makeup techniques could offer a superficial enhancement, but Vincent's strategy was more dependent on a complete overall persona that also aligned with Jerome's social status. Changing his posture could assist in adopting a more confident demeanor, and engaging in rigorous training could improve physical fitness, but these actions are not as direct or impactful as altering his outward style to mirror Jerome's established persona.