The correct answer is A. corporate planning.
Corporate planning is the process of setting long-term goals and objectives for an organization and developing strategies to achieve those goals. It is a top-down approach to planning that involves senior management in setting the direction for the organization.
Divisional planning is the process of setting goals and objectives for a division within an organization. It is a bottom-up approach to planning that involves managers at the divisional level in setting the direction for their division.
Unit planning is the process of setting goals and objectives for a unit within a division. It is a bottom-up approach to planning that involves managers at the unit level in setting the direction for their unit.
Department planning is the process of setting goals and objectives for a department within a unit. It is a bottom-up approach to planning that involves managers at the department level in setting the direction for their department.
Corporate planning is the most important type of planning because it sets the overall direction for the organization. Divisional planning, unit planning, and department planning are all important, but they are subordinate to corporate planning.