Answer-
1.Growth in size -as the firm size gradually increases there is a greater need of coordination to integrate the work of various organisational departments .
2.Functional differentiation- there are different departments in each firm ,They all have distinct objectives ,strategies and policies .Hence to avoid any disharmony coordination among all of them is required .
3.Specialisation-Specialists are hired in order to perform a particular task ,such as hr ,finance and such other managers who have speciality in their field and here coordination helps in maintaining harmony