Answer: b. relationship selling
Step-by-step explanation:
Relationship selling refers to a process by which a relationship is built between customers and salespersons. This works when the salesperson takes an active interest in the life of the customer such that they feel satisfaction.
Diego is a salesperson who sells to Homer Manufacturing. In taking employees of the company out and even giving them gifts, he is building a relationship with them and being involved in their personal life. This is therefore relationship building.