Answer:
C) keep doing everything himself.
Step-by-step explanation:
Marvin has started the restaurant alone and had to do everything, as the business grows tasks that need to be done will be too great for one person to do. Especially when we want a good, quality output.
So Marvin will need to hire staff that specialize in each area to improve the efficiency of that department.
For example he will need to hire servers to attend to customers, hire someone to manage the accounting and tax process of the business, and hire someone to manage the restaurant as a whole.
This will enable Marvin carry out other tasks focused on business growth like getting the best deals from suppliers.