In order for sales reps to be looked to as trusted advisors, what is the MOST important thing they must first do?

 In order for sales reps to be looked to as trusted advisors, what is the MOST important thing they must first do?
  A)  Be in their industry for 10 or more years.
  B)  Tell the prospects what to do in order to get quick wins.
  C)  Build up their personal brand as a thought leader in their industry.
  D)  Have a lot of LinkedIn connections.