Final answer:
Oceanic crust is primarily composed of basalt, has a thickness of about 6 kilometers, and makes up the ocean floor. Contrary to some misconceptions, it is not watery granite, nor does it form silicon beaches, and it's not necessarily the oldest crust. Option number c is correct.
Step-by-step explanation:
The characteristics of oceanic crust include being composed mostly of basalt, which is a volcanic rock that forms from the cooling of lava. This basalt composes the ocean floor and is typically about 6 kilometers thick. Oceanic crust is not watery granite nor is it what makes up silicon beaches; instead, it is comprised of silicate minerals like silicon, oxygen, iron, aluminum, and magnesium. It is also a misconception that oceanic crust is the oldest; in fact, due to the constant recycling of tectonic plates, some of the oceanic crust can be quite young compared to the continental crust.
Oceanic crust differs from continental crust, which is thicker, less dense, and made predominantly of granite. The oceanic crust has a density of about 3 g/cm³ and makes up about 0.3% of the total mass of Earth. As a result of its composition and density, oceanic crust forms deep oceanic basins when it sinks into the mantle, creating a foundation for the planet's oceans.