Answer:
The correct answer is letter "C": We request a brief extension to complete the report.
Step-by-step explanation:
In business writing, it is important to provide messages with objectivity and clarity avoiding hidden verbs, redundancy, and exuberance which could distract the readers making them difficult to understand what is intended to be expressed.
Besides, positive and courteous messages are necessary to avoid confusing readers while being polite. These messages do not use words such as complaints, failed or criticism. Thus, the segment:
We request a brief extension to complete the report;
is the most straight-forward sentence reflecting positive and courteous messages.