When Implementing an Action Plan, What Is the Worst Thing

When implementing an action plan, what is the worst thing an entrepreneur could do?

A) Scrap all of their efforts when they find the business plan is ineffective
B) Focus their efforts on modifying their business plan while attempting to implement it
C) Switching to a contingency plan simply because the initial plan did not work out
D) Make constant concessions in their plan until it does not resemble the original plan