Sara is a repairperson for Telecommunications Company (TC). The job requires driving to remote areas to make repairs under any conditions. Sara has had the job longer than other employees. Sara applies for a promotion to a supervisory position that requires constant communication with others in the field. TC rejects the application on the ground that Sara is hearing impaired. TC acknowledges that Sara is otherwise qualified, but asserts that it "needs someone who does not have a hearing disability." Sara files a suit against TC under the Americans with Disabilities Act of 1990. What is the issue in this problem, and what are the relevant considerations on which its resolution depends?