Step 1: Understanding the Concept:
A divisional structure groups activities based on products. Each division is semi-autonomous and contains all the functions (production, sales, etc.) needed to manage that product line.
Step 2: Detailed Explanation:
In a divisional structure, division heads have the authority to make decisions independently for their specific product line (e.g., Commercial vs. Passenger vehicles). This autonomy fosters faster decision-making (flexibility) and encourages managers to take initiative to improve their specific division's performance. Options (b), (c), and (d) describe advantages of a \textit{functional} structure.
Step 3: Final Answer:
The benefit is (a) promoting flexibility and initiative.