James employs an apprentice in his guitar store who gets firsthand knowledge of craftsmanship and the process involved in becoming a professional luthier. This allows James to have a reliable hand who can assist him in his work without requiring him to hire a professional luthier. It also enables him to use his financial resources on procuring high-quality materials to make the guitars. The opportunity of _____ is highlighted in the given scenario.
选项：

A: having lower overhead costs
B: exploiting market niches
C: using technology
D: providing personal customer service