Final answer:
The sentence 'Please understand that our budget has been cut back' is most appropriate for conveying bad news because it is factual and professional, offering an explanation in a clear manner without placing blame.
Step-by-step explanation:
The question is asking to identify which sentence has an appropriate tone for delivering bad news. When communicating unfavorable news, it is vital to do so with a tone that is professional, empathetic, and clear. Of the options provided, the most suitable and professional choice without coming across as insensitive or overly apologetic is "Please understand that our budget has been cut back." This option is factual and offers an explanation for the action, which can help the recipient understand the situation. It does so without placing blame or causing undue distress.