C because a market research helps when you are buying something which he is (car) and this is a secondary resource because it is recommended by someone rather than them finding the research himself.
Market research refers to gathering information to analyze the market and understand the needs of the group of people. Whereas, secondary research is a research which involves gathering information from the already existing data.
In the above scenario, Ricardo through the method of market research gathers information about how people fulfill their need o9f gathering information about used cars. Through secondary research he gathers information upon how consumer gets information by conducting a survey.
