context: The definition of imperialism has not been finalized for centuries and was confusedly seen to represent the policies of major powers, or simply, general-purpose aggressiveness. Further on, some writers[who?] used the term imperialism, in slightly more discriminating fashion, to mean all kinds of domination or control by a group of people over another. To clear out this confusion about the definition of imperialism one could speak of "formal" and "informal" imperialism, the first meaning physical control or "full-fledged colonial rule" while the second implied less direct rule though still containing perceivable kinds of dominance. Informal rule is generally less costly than taking over territories formally. This is because, with informal rule, the control is spread more subtly through technological superiority, enforcing land officials into large debts that cannot be repaid, ownership of private industries thus expanding the controlled area, or having countries agree to uneven trade agreements forcefully.
question: What subtle tool can be used in an informal imperialistic situation to expand a controlled area?
answers.text: ownership of private industries technological superiority technological superiority ownership of private industries technological superiority,