Complex sentence: The requirement that SU (3) c should be local--that its transformations be allowed to vary with space and time--determines the properties of the strong interaction, in particular the existence of eight gluon types to act as its force carriers.
Split into simpler sentences: The requirement that SU (3) c should be local means that its transformations be allowed to vary with space and time. This determines the properties of the strong interaction, in particular the existence of eight gluon types to act as its force carriers.