Answer;
d} On continental land masses
Explanation;
-The oldest rocks are located on continents, usually away from the ocean. The mid-ocean ridges are, in fact, home of some of the youngest rocks. The reason for this is what is called sea-floor spreading. Mid-ocean ridges form at places where oceanic plates diverge, or move apart. As this happens, magma rises from within the Earth to fill the gap. The magma cools and solidifies, creating new seafloor. This process continues as the plates continue to spread apart.