Step 1: Understand the role of motivation in management.
Motivation is the process of encouraging employees to achieve higher performance and work towards organizational goals. It is the most significant incentive-giving function of management.
Step 2: Evaluate the options.
- Staffing and organization are essential for ensuring the right people and structure are in place, but motivation is the key to driving performance.
- Motivation directly influences employee engagement and performance, making it the most critical incentive-giving function.
Step 3: Conclude.
Motivation is the function that provides the maximum incentive to employees, ensuring they perform at their best.
Final Answer:
\[
\boxed{\text{Motivation}}
\]