Which of the following is not true? a. The springing line of an arch is an imaginary line that goes between the two points from which the arch springs into its curve. b. Architects are concerned only on the aesthetic appeal of architecture. c. A corbel dome is essentially created by rotating corbel arches. d. The keystone of an arch is the last piece put in and holds the voussoirs in place. Please select the best answer from the choices provided A B C D