Right answer is (a) Ashlar Chamfered masonry
For explanation I would say: Ashlar Chamfered masonry is special form of Rock faced ashlar masonry in which the strip provided around the perimeter of the exposed face is chamfered or bevelled at an angle of 45° by means of a chisel to a depth of 25 mm. Due to this, a groove is formed in between adjacent blocks of stone.
