Which of the following promotional tools requires the most long$-$term commitment and is the most expensive to use on a per contact basis?

a$.$ Public relations

b$.$ Direct marketing

c$.$ Sales promotion

d$.$ Personal selling

e$.$ AdvertisingWhich of the following promotional tools requires the most long$-$term commitment and is the most expensive to use on a per contact basis?

a$.$ Public relations

b$.$ Direct marketing

c$.$ Sales promotion

d$.$ Personal selling

e$.$ Advertising