Which is an example of using collaboration?

Question $6$ options:

a$)$

Two entrepreneurs sit in their favorite coffee shop to observe and listen to patrons to spark new ideas.

b$)$

An entrepreneur goes for daily walks and thinks about how their own work experience might be used to improve their neighborhood.

c$)$

An entrepreneur describes an idea for a virtual car buying experience to friends over dinner.

d$)$

Three friends have dinner and write down all the ideas they generate, no matter how unrealistic the ideas seem to be$.$