For a transverse wave travelling along a straight line, the distance between two peaks (crests) is 5 m, while the distance between one crest and one trough is 1.5 m. The possible wavelengths (in m) of the waves are:
(1) 1, 3, 5, .....
(2) 11,31,51,…
(3) 1, 2, 3, .....
(4) 21,41,61,…