The part of an arch that projects slightly from the wall and the point where the arch springs from is called the a. voussoir c. pendentive b. impost d. keystone select the best answer from the choices provided a b c d

D keystone

Explanation:

The Keystone slightly protrudes from the wall at the point where the arch springs from- a pendentive is a curved triangle of vaulting formed by the intersection of a dome with its supporting arches , a Voussoir is a wedge-shaped or tapered stone used to construct an arch, and an impost ( the second closest to the definition ) is that part of an arch from which the arc swings upward.

option c (nickel) is not found in earth's crust. the earth's crust basically contains eight (8) elements namely: oxygen, silicon, aluminum, iron, calcium, sodium, potassium and magnesium (listed in order of abundance).