What does the last sentence in the 3(上标)rd paragraph mean according to the passage

A．The patient is seriously ill because of lack of water in the well.
B．The patient can be saved if he has enough money to solve the financial problem.
C．It's too late for small business owners to realize the gravity of the problem because they have used up their money.
D．It's too late for small business owners to realize the gravity of the problem because they have used up their business.