Amongst the following molecules the one with the largest distance between the two adjacent carbon atoms is

H3C — CH3                          Ethane               Ethene                   Benzene                    Ethyne1                            2                              1.5                             3                                                         C — C Bond length order: Ethane > Benzene > Ethene > EthyneAs the number  of bonds between two carbon atoms increases bond length decreases.