Step 1: Understanding the question.
The question refers to the function that ensures different parts of the organisation work together efficiently.
Step 2: Analyzing the options.
- Planning: Planning involves setting objectives but does not specifically address the coordination of efforts between units.
- Organising: Organising refers to arranging resources and tasks but does not directly address the synchronization of efforts.
- Controlling: Controlling involves monitoring and correcting performance but does not synchronize efforts across units.
- Coordination: Coordination ensures that different units work together with the right timing, effort, and resources to achieve objectives effectively.
Step 3: Conclusion.
The correct answer is Coordination, as it is directly related to synchronising efforts across the organisation.
Final Answer:
\[
\boxed{\text{The correct answer is (4) Coordination.}}
\]