Artur,who Has a Disability,is an Employee of Banquet & Event

Artur,who has a disability,is an employee of Banquet & Event Facilities & Services,Inc. After the installation of new doors on the entrance to Banquet's hall,Artur finds it nearly impossible to enter and exit. For repeatedly failing to be on time,Banquet replaces Artur with Carter,who does not have a disability.
-To successfully defend against Artur's claim,Banquet will have to show that

A) Artur consistently failed to meet the essential requirements of his job.
B) Banquet cannot make changes to the doors without undue hardship.
C) Carter is qualified for Artur's position.
D) the doors were not installed as an act of intentional discrimination.