Customers of Harley$-$Davidson are highly satisfied with the bikes and the repair services provided by the company. They also believe the company responds to any complaints fairly and adequately. The extent to which the consumers believe the processes involved in processing a transaction, performing a service or handling a complaint is fair is referred to as $\_\_\_\_\_\_\_\_.$

a$.$ procedural justice

b$.$ affirmative action

c$.$ distributive justice

d$.$ antitrust law