The "who" encompasses anything related to the people in the startup.
Solving the who involves making decisions about related matters. How
many co-founders will there be? Who will the co-founders be? What is
the ownership share of each co-founder? What is the management
structure? What skills are needed? What skills do people have? Will
there be employees? How will decisions be made? Is the group
compatible? Can we work together through adversity? Do the
co-founders share similar values and philosophies? Is everyone
pulling in the same direction?