Final answer:
The differential revenue for the Allen Company in 2021 after introducing a new service is $169,000, which is the additional sales generated by the new service.
Step-by-step explanation:
The question asks for the differential revenue for the Allen Company for the year 2021 after introducing a new service. Differential revenue refers to the additional revenue generated from a particular action or decision. In this case, the new service is projected to generate $169,000 in sales revenue. This is the additional amount compared to the previous year, so the differential revenue for 2021 would be $169,000 (Option C), assuming that revenues from other services remain the same. It is important to note that differential revenue is not adjusted for costs; it only reflects the change in revenue.