Seven boys B1, B2, B3, B4, B5, B6 and B7 are sitting around a circular table, facing towards the centre (not necessarily in the same order). B3 is second to the left of B6. B1 is third to the left of B3. B7 is third to the left of B6. B4 is not the immediate neighbour of B6. B2 is not the immediate neighbour of B1. B5 is the immediate neighbour of B1 and B6. Three out of the following four options are similar by a certain logic and form a group. Which of the following does NOT belong to that group?