The correct option is B Formation of spindle fibres.
Centrioles are minute submicroscopic sub-cylindrical structures which usually occur in pairs, inside a specialised cytoplasm called as centrosphere or kinoplasm. The whole complex is called as centrosome, having two centrioles lying at right angles to each other. Centrioles are essential for formation of spindle fibres, which attach to the kinetochore discs present at the centromere and are thus, responsible for the movement of chromatids during chromatid separation.