The correct answer is (1)
Places where plate are coming apart are called divergent boundaries. As the plates separate along the boundary, the block between the faults cracks and drops down into the soft, plastic interior(the asthenosphere). The sinking of the block forms a central valley called a rift.
In the ocean, mid - ocean ridges are formed when divergent tectonic plates processes are moving two pieces of oceanic crust way from each other. This process is also responsible for what is called seafloor spreading
