Final answer:
Ken should create a class for the R&D department in his accounting software and specify it in all related transactions to efficiently track them.
Step-by-step explanation:
To best keep track of which transactions are related to the Research & Development (R&D) department in his company, Ken should create a class for the R&D department and specify it in all department-related transactions. By doing so, he can easily filter or generate reports based on this class in his accounting software, thus keeping the transactions organized and easily accessible. This is more efficient than creating a separate company file, which could complicate the consolidation of financial information, or exporting reports to Excel after every transaction, which would be time-consuming and could lead to errors through manual handling. So, the correct answer would be option b). The use of accounting software classes allows for better tracking and reporting without the drawbacks of the alternative methods and ensures that the financial data remains integrated within the overall company finances.