Number of cyclic isomers (structural and stereo) possible with the formula, C₄H₈ is

(1), (2), (3)--cis and trans….four acyclic isomers ;

(4), (5)--------- ---------------------------------two cyclic isomers…both structural ;

(1), (2), (3)--cis and trans, (4), (5)…..total six isomers ;