Answer:
a. Continental crust is less dense than oceanic crust.
d.Oceanic crust is different from continental crust because most continental crust was formed from cooling magma.
Explanation:
The part of earth's crust that lies beneath the ocean floor is called the oceanic crust.
Continental crust is the portion of earth crust which forms the landmass.
The different layers in Continental crust is composed of by cooling of magma to form igneous rocks. It is different from the oceanic crust. Also oceanic crust is more denser than continental crust.