What is the full form of C.O.M.P.U.T.E.R ?

1   C = Commonly       2    C = Commonly           3    C = comman           4     C = comman
     O = Operating              O = Operating                  O = Office                      O =  optimum
     M = Machine               M= Machin                       M = Machin                   M=  Mobility
     P = Particularly             P = part                            P = part                          P =  Particularly
     U = Used for                U = Unit                           U =  Unit                        U=   Used for
     T = Technical and         T =  Training                     T =  Training                   T = Technical and
     E = Educational            E =  Effect                        E =Educational                E = Educational
     R = Research.              R = Report                       R = Research                   R = Report

Answer :   1