In their 2014 paper, Sugiura and Yamazaki tested the effectiveness of caterpillar hairs as a defense against predators by performing which of the following activities?
1) They found caterpillars with and without hair and fed them to birds
2) They experimentally added hair to hairless caterpillars and fed them to birds
3) They experimentally shortened hairs of one caterpillar and measured predation success by beetles
4) They genetically modified hairless caterpillars and measured predation success by beetles