Identify the correct statement for change of Gibbs energy for a system `(DeltaG_(system))` at constant temperature and pressure:
A. if `DeltaG_(system)=0` , the system is still moving in a particular direction
B. if `DeltaG_(system)=-ve` , the process is not spontaneous
C. if `DeltaG_(system)=+ve` , the process is spontaneous
D. if `DeltaG_(system)=0` , the sytem has attained equilibrium