Each term of the series is obtained by multiplying the previous term by 3. Therefore the particular order is: 5, (5 × 3 = 15), (15 × 3 = 45), (45 × 3 = 135), (135 × 3 = 405), (405 × 3 = 1215), (1215 × 3 = 3645), ...... and so on. Hence, alternative (e) consists of the wrong term.