Final answer:
Alfred Wegener introduced seafloor spreading and laid the foundation for plate tectonics with his theory of continental drift.
Step-by-step explanation:
The scientist who introduced seafloor spreading and laid the foundation for plate tectonics was Alfred Wegener. In 1920, Wegener proposed the theory of continental drift, which suggested that the Earth's continents were once joined together in a single supercontinent called Pangea and have since moved apart. Although his idea was initially met with skepticism, it paved the way for further scientific research that eventually led to the development of plate tectonics.