Answer:
A. Through geologic forces leading to continental drift.
B. It can take up to millions of years.
Step-by-step explanation:
A. Continents rest on tectonic plates (a large slabs of rock). The plates are usually moving and interacting with one another. Seafloor spreading zones and giant rift valleys are the sites where tectonic activity are done.
However, in the process of seafloor spreading, molten rock emerges from within the Earth and produces an oceanic crust (a new seafloor) to the edges of the old one. Seafloor spreading occurs along giant underwater mountain ranges (also referred to as mid-ocean ridges).
Then, as the seafloor grows wider, the continents on opposite sides of the ridge move away from each other over time to experience a define continental drift.
B. The seafloor spreading rates is as low as 2.5 centimeters per year and take up to millions of years to see a well defined drift.