What tactic did Filipino insurgents use to undermine American power? A:self-rule B:concentration camps C:guerilla warfare D:insurgency

The correct answer is C. Guerilla warfare. It is a small scale type of warfare where the guerillas are more of a nuisance than a real enemy. Unlike regular warfare where you fight on large fields or in cities or similar, guerilla warfare relies on missions like sabotage or bombings or arson or anything similar that will lower the morale of people. Small groups of soldiers come out of nowhere, blow something up, and retreat, and so on and so forth.