What product was Kwolek trying to improve when she invented Kevlar?

The correct option is Tires.

Explanation and Historical Context:

In 1964, chemist Stephanie Kwolek was working at DuPont to develop a lightweight, strong fiber to replace steel in radial tires due to an anticipated gasoline shortage. During her research, she synthesized poly-p-phenylene terephthalamide, a polymer that formed liquid crystal solutions.

When spun into fibers, this material demonstrated exceptional strength and stiffness, ultimately leading to the commercial invention of Kevlar. Although Kevlar is widely known today for its application in bulletproof armor and brake linings, its initial target application was to improve automobile tires.