Given that startups can be flexible in their business model,what general guide should they follow?

A) Existing models should not be changed.
B) Existing models should be replaced frequently.
C) Existing models should be prepared to adjust as markets change.
D) Existing models require annual updating.

Startups should be prepared to adjust their business models as markets change. Flexibility is one of the key advantages of being a startup, and being able to pivot your business model can be necessary for survival in a rapidly changing market. However, this doesn't necessarily mean that existing models should be replaced frequently or require annual updating. It's more important to be able to adapt as needed rather than sticking to a rigid plan.