which of the following is most likely the next step in the series?

D

Reasoning:

the pattern keeps the previous color and alternates between blue and red.  The pattern is also increasing in number by 1.  Therefore there would be no reason for the fourth step to change previous color or numbers.  That eliminates A and B.  For C, since the pattern is adding a different color clockwise in each step, it is more likely that the pattern will continue to alternate, therefore D is most likely.