The voussoir placed at crown of an arch, is known as a A. Key B. Soffit C. Springer D. Haunch

The correct answer is A. Key.

A voussoir is a wedge-shaped stone or brick that is used to construct an arch. The key is the voussoir that is placed at the crown of the arch. It is the last voussoir to be placed, and it locks the other voussoirs in place.

The other options are incorrect.

• A soffit is the underside of an arch.
• A springer is the voussoir that rests on the abutment.
• A haunch is the part of an arch that is between the springer and the crown.