Financial institutions are primarily responsible for which of the following?

Financial institutions play a critical role in the economy by facilitating the flow of money and ensuring the efficient functioning of financial markets. Their primary responsibility is to conduct financial transactions, which includes activities such as accepting deposits, providing loans, processing payments, and offering investment products. This core function allows individuals and businesses to carry out their financial needs effectively.

In contrast, providing legal advice, managing employee payroll, and marketing and advertising pertain to different sectors or specific roles. Legal advice is typically offered by legal professionals such as attorneys; managing employee payroll generally falls within the human resources or accounting departments of businesses; and marketing and advertising are essential functions within the realm of business development and promotion. Thus, the distinct focus of financial institutions on facilitating financial transactions underscores why that choice is the accurate answer in this context.