How is investment income defined?

Investment income is defined as income earned from investments, which typically includes earnings from financial assets such as stocks, bonds, mutual funds, and real estate, rather than from regular employment or self-employment activities. It encompasses passive income streams, which are generated without direct involvement in the operations of a business.

The correct choice highlights that investment income arises from passive events that do not constitute active business operations. This differentiates it from wages or salaries earned through employment or profits from activities where one is actively engaged in running a business. Investment income can include dividends, interest, and capital gains, all of which fit the criteria of being generated passively.

The other options, while related to income, focus on different categories not specific to investment income. Regular employment and self-employment income pertain to active participation in earning income, and net profits from selling assets, while related to investments in certain contexts, do not encompass the broader definition of ongoing investment income.