Answer:
At point 4
Step-by-step explanation:
Subduction is a geologic process which occurs at convergent plate margins.
Subduction occurs when a denser lithospheric plate goes beneath the lighter one. Generally, the lithosphere is made up of the crust and part of the mantle. The two moves slowly on the weak and plastic asthenosphere.
In a convergent plate margin, two plates comes together. When two plates comes together, it is either we have collision or subduction. When subduction occurs, denser plates goes beneath the less dense ones.
The average density of the continental crust is 2.9g/cm³ while that of the oceanic crust is 3.3g/cm³. The oceanic crust geos beneath the continental crust because it is denser. This is subduction.