Translating lean startup

Which do you think is hardest in your company, or your own work?

A. Coming up with ideas that are truly new and different?

B. Testing and iterating those ideas to create products or services that actually work (i.e. they attract customers & make money)?

C. Scaling up those profitable innovations so that they have a significant impact across the entire business?

Why do you think the step you chose is the hardest for you?