The correct answer is option 1, Felix d`Herelle and Frederick Twort. Bacteriophages are viruses that infect bacteria and were first discovered independently by Felix d`Herelle and Frederick Twort. In 1915, d`Herelle, a French-Canadian microbiologist, observed that a filtrate of bacteria-free liquid could still cause bacterial infections. He named these filterable agents "bacteriophages," which means bacteria-eaters. Around the same time, Twort, an English bacteriologist, also discovered similar filterable agents that could infect bacteria. Both scientists made significant contributions to the understanding of bacteriophages. While d`Herelle is often credited as the discoverer of bacteriophages, Twort`s work laid the foundation for their discovery. Together, their research paved the way for further exploration and understanding of these unique viruses.