Please choose the correct ending to complete the given sentence: Youth: [header] How to make a lot of money by the age of 20 [title] Choose a business focus appropriate for your circumstances. [step] If you are 14 and still in school, dog walking is more appropriate, for example, than if you are married with a child and 18 years old. Focus your initial energy on figuring out who your business will serve and how.

Ending1: [substeps] Think about potential investors you can market to. In the earlier phases of investing, your target customers will most likely be willing to pay for what you start. Ending2: [title] Consider the high number of hours you are willing to work. [step] Although $60 is lower for entrepreneurs compared to $200, if you live long enough, you will still be eating. Ending3: Identify a problem or inconvenience that many people have and create a business idea based on solving this problem. Think about what product or service you could offer. Ending4: [substeps] On a dog walking job, you won't have to worry as much about the training of a dog or the quality of the equipment you use. Your business focus is on developing and trusting the people within your business.

Answer format: ending1/ending2/ending3/ending4