The problem figure shows the top view of objects. Looking in the direction of the arrow, identify the correct elevation, from amongst the answer figures.
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The four identical triangular prisms each show three vertical edges, two of them close together on the left; check for extra or missing lines.
The plan has four identical triangular prisms, each with its apex pointing to the right: two at the back and two in front. Seen from the arrow side, each prism shows its slanted side face and its short left face edge-on, so it appears as a rectangle with one narrow strip at its left end, i.e. three vertical edges in all: the left edge, a second edge a little to the right of it, and the right edge. The two prisms on the left overlap in the elevation (one in front of the other), and so do the two on the right, with the front prisms hiding the lower part of the back ones. Option (1) draws an extra line inside the nearest right prism. Option (2) draws an extra line inside the front-left prism. Option (3) draws an extra line on the back-right prism. Option (4) has exactly the right set of lines on all four prisms. Answer: (4) elevation (4)
