Final answer:
The correct answer is option 4: Whether it is part of the lithosphere, as both continental and oceanic crust are part of the Earth's lithosphere. The thickness, composition, and elevation are actual differences between continents and oceans.
Step-by-step explanation:
To answer which of the following is NOT an important difference between continents and oceans: The thickness, composition, and density of the crust are indeed important differences between continental and oceanic crust. Continental crust is thicker and composed mainly of granite, while oceanic crust is thinner and primarily made up of basalt. Both types of crust have similar densities of around 3 g/cm³. However, being part of the lithosphere is not a difference because both the oceanic and continental crust form part of Earth's lithosphere, which includes the crust and the uppermost part of the mantle. The elevation of the crust is another visible difference, as continental crust rises higher due to its lower density, while oceanic crust forms basins that become the planet's oceans when filled with water.