Answer: One of the ways in which Kim earns a living is C. working as a bartender.
Step-by-step explanation: 'To earn a living' means to earn the money that is required to pay for basic needs, such as food and clothing. Therefore, in order to earn a living, it is necessary to have a stable job. In that way, option C. is the correct answer since it makes reference to a bartender job, which is a stable one. In other words, it is a job for which Jim receives enough money to live. In contrast, (A.) helping Tilly in his garage does not imply earning money for doing it, and (B.) occasionally driving a bus is not a stable job, something that the word 'occasionally' indicates.