The correct option is C Removal of apical dominance and promotion of intercalary meristems
Apical dominance involves withdrawal of root manufactured cytokinins towards apical bud which in turn makes the lateral and intercalary meristem cytokinins deficient. Cytokinins deficiency suppresses growth of lateral and intercalary meristem as cytokinins are the hormones of cell division. Mowing causes cutting off the apical portion of branches to induce growth which in turn lowers the amount of auxin synthesized as shoot apex. The lowered auxin synthesis allows translocation of cytokinins to lateral and intercalary meristem stimulating cell division and growth in them. Since grasses are monocots, intercalary meristem is responsible for their growth, not lateral meristem. Thus, the correct answer is C.