Three non-overlapping regular plane polygons, at least two of which are congruent, all have sides of length 1. The polygons meet at a point A in such a way that the sum of the three interior angles at A is 360∘. Thus the three polygons form a new polygon with A as an interior point. What is the largest possible perimeter that this polygon can have?
<spanclass=′latex−bold′>(A)</span>12<spanclass=′latex−bold′>(B)</span>14<spanclass=′latex−bold′>(C)</span>18<spanclass=′latex−bold′>(D)</span>21<spanclass=′latex−bold′>(E)</span>24