A cleaning crew works in an office building. Mike is a member of the crew. He wears a prosthetic leg, which enables him to walk very well, but climbing steps is painful and difficult for him. Although he can perform his essential functions without problems, he cannot perform the marginal function of sweeping the steps located throughout the building. The marginal functions of a second crew member include cleaning the small kitchen in the employee's lounge, which is something that Mike can perform. Mike requests his employer to allow him to clean the kitchen rather than sweep the steps. His employer refuses to act on Mike's request. Is the employer legally permitted to deny Mike's request?