A startup is in the "Model" phase of the startup J Curve. They have found a winning business model and are now scaling their business. They are hiring new employees, building a scalable infrastructure, and raising capital. However, they are facing some challenges with their team. Some of the employees are not meeting expectations and the company culture is starting to suffer. What should the startup do? a. Fire the underperforming employees and hire new ones. b. Invest in team-building exercises and activities. c. Create a more clear and concise vision for the company. d. A combination of (a), (b), and (c)