Answer:
Illustration A
Step-by-step explanation:
Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.
A. Is seafloor spreading, The diagram shows magma is rising due to an upwelling convection current in the magma. The arrows show that the crust is spreading.
B. shows the occurrence of a hot spot. This is when there is a an upwelling of magma because of the currents in the mantle. So, as the ocean crust moves over the hot spot, volcanoes are formed.
C. Shows a subduction zone. One ocean crust is pushed under another continental crust a subduction zone is formed. The melted crust becomes magma that forms an island arc of volcanic islands.
D Shows the crust spreading. This is not oceanic spreading because it is not in the ocean.
Hope this helps : D