Final answer:
The true statement is that both voice mail and email should be designed with a focus on a single topic for clarity and efficiency. Proofreading and a relevant subject line are essential. Complex issues might require direct communication.
Step-by-step explanation:
The statement that voice mail should be designed with the same principles as used in designing emails, and should focus on one topic, is True. Communication, whether through voice mail or email, should be clear and concise. When designing an email, it's imperative to use a relevant subject line, keep paragraphs short, and focus on a single topic to ensure the recipient can quickly grasp the main point. Similarly, when leaving a voice mail, you should identify yourself, state the purpose of the call succinctly, and keep the message focused on one issue to facilitate a clear and efficient response.
Proofreading your email ensures clarity and professionalism. Proofreading is vital to convey your message appropriately and without errors. Emails that address multiple issues can become confusing and harder to prioritize, so it's best to stick to a single topic. When an issue is too complex to be explained briefly, consider direct communication instead of a lengthy email or voice mail.