In each of the following questions, there is a set of four figures labeled 1, 2, 3 and 4 called the Problem Set followed by a set of four other figures labeled a, b, c and d called the Answer Set. Fig.(3) contains a question-mark. Select a suitable figure from the Answer set which will substitute this question mark so that a series is formed by the figures 1, 2, 3 and 4 taken in order. The alphabet of the selected figure is the answer.