Why Is Earth's Continental Crust Lower in Density Than Seafloor

Why is Earth's continental crust lower in density than seafloor crust?

A) Continental crust comes from Earth's inner core while seafloor crust comes from the outer core.
B) Continental crust is made as the lowest- density seafloor crust melts and erupts to the surface near subduction zones.
C) Continental crust comes from volcanoes while seafloor crust comes from geysers.
D) Continental crust is made from a low- density volcanic rock called basalt.