Answer:
d. At work
Step-by-step explanation:
Researching a new job at work is most appropriate. It means using company resources and time to pursue personal interests.
Researching another job while at work is also unethical. One is paid for services and their input to a company. But when one is researching another job at work, it suggests they want to be paid for doing their personal things, and yet they are thinking of leaving.