Colour is believed to be the source of the strong force , in the same way as electric charge is the source of the electromagnetic force .
(Colour; is believed; ) (Colour; to be; the source of the strong force) (electric charge; is; the source of the electromagnetic force) (electric charge; is the source of; the electromagnetic force)
Colour Colour electric charge electric charge
is believed to be is is the source of
the source of the strong force
the source of the electromagnetic force
the electromagnetic force