Brad Is a Real Estate Agent

Brad is a real estate agent. He recently had an idea for a program to help perform appraisals more quickly and more accurately. He has a buddy who is a programmer that has helped him develop a detailed description of what the program will do and how it differs from existing apps. Now, Brad has taken this description and shown it to a number of fellow real estate agents to see if his idea appeals to them. What is Brad engaging in?

A) prototype outsourcing.
B) test marketing.
C) concept testing.
D) word-of-mouth promotion.