Layla is one of five sales managers at a sports equipment company. She and the other sales managers are under pressure from management to keep their teams of sales representatives motivated and hitting their sales quotas. Because of that, Layla has studied psychology and motivation and is always looking for better ways to motivate her team. The biggest factor in motivation for sales representatives is enjoying sales as a career. This means that the best way for Layla to build a motivated sales team is to: 

a$.$implement a straight commission compensation plan

b$.$ provide all employees with the same benefits

c$.$provide a mix of external and internal rewards

d$.$ offer cash bonuses for the top sellers each month

e$.$ teach employees to cold$-$call more efficiently