Option 1 -> When income rises, there's no economic basis for spending on imports to decrease.
Option 2 -> Spending patterns change with income levels; imports won't remain constant.
Option 3 -> Higher income leads to increased consumption of all goods, including imports.
Option 4 -> The relationship is generally clear and positive, not uncertain.
Hence, Option 3: Increase -> When income increases, consumers have more disposable income and tend to spend more on all types of goods, including imported goods. This follows the economic principle of marginal propensity to import (MPM), which states that as national income rises, imports tend to rise as well. Just as domestic consumption increases with income, so does the consumption of foreign goods and services. This is why imports are considered positively related to income levels in economics. -> correct