The right option is; ultramafic
Peridotite is a dense, coarse-grained plutonic rock that is composed mostly of the minerals olivine and pyroxene. The composition of peridotite is ultramafic, as the rock has less than 45% silica and it has high magnesium content with significant amount of iron. Peridotite is economically valuable because it is a source rock for diamonds, and it is the major constituent of the upper part of the Earth's mantle.