Answer : 4. "Dr. Wallace H. Carothers"
Explanation :

Nylon was invented by Wallace Carothers, an American chemist, while he was working at the DuPont chemical company. Carothers and his team at DuPont successfully synthesized the first nylon, known as Nylon 6,6, in 1935. Nylon became the first commercially successful synthetic fiber and found wide-ranging applications in textiles and various industries.