Dandy is a young male chimpanzee. Recently, he did something that surprised some scientists. The scientists had buried some grapefruit in the sand. Dandy knew where the grapefruit was, but when the other chimps were in the area, Dandy pretended that he did not know the place. Later, when the other chimps fell asleep, Dandy went right to the spot where the grapefruit was hidden, dug it up, and ate it. Amazingly, Dandy was able to __________

윗글의 빈칸에 가장 알맞은 말은?

1 commun1 communicate
2 follow others
3 use tools
4 make a plan
5 find hidden food

정답은 4번인데요.. 왜 그런지 잘 모르겠어요.. 해석은 다 되는데, 정답을 모르겠어요ㅜㅜ 댄디가 체계적으로 무슨 계획을 세운건 아니잖아요ㅜㅜ 왜 4번이 정답인지 가르쳐주세요!~~~