Answer:
Option (3)
Step-by-step explanation:
The oceanic crust has a thickness of about 7 to 10 km on average, which is much thinner than the continental crust. In order to obtain the rock sample from the mantle, drilling must be done through the rocks of oceanic crust. It is because the depth from the seafloor up to mantle will be much lesser than the depth from the surface of the continental crust to the mantle.
It will require a comparatively lesser amount of money for excavation, in comparison to the drilling done from the continental surface.
Thus, drilling is more favorable to obtain mantle rocks from the oceanic crust.
Hence, the correct answer is option (3).