Answer: Option (c) is correct.
Step-by-step explanation:
Correct option: Unplanned inventory investment.
Unplanned inventory investment is a component of investment spending. The other component of investment spending is planned inventory investment.
Unplanned inventory investment occurs when actual sales are more or less than the company's expected sales which results in unplanned changes occurred in the inventories.
Hence, in the Keynesian-cross model, actual expenditures differ from planned expenditures by the amount of Unplanned inventory investment.