Concept:Small and medium enterprises need a simple structure that gives clear authority and supports quick decision-making.
Explanation:In a line structure, authority flows directly from the top manager down to subordinates.
This creates a clear chain of command and makes responsibility easy to identify.
Because the business is small, the owner or manager can supervise all workers directly.
Decisions are made faster because there are fewer levels of management and no complex specialists.
Functional structure, on the other hand, divides work into departments such as marketing, production, and finance, which is more suitable for large organisations.
Staff structure and committee structure also involve extra advisory or group decision-making layers that small firms rarely need.
Therefore, a line structure is the most practical and efficient option for a small or medium enterprise.
Answer:A. line structure.