"사과를 젓가락으로 자르세요."
Translation:Cut the apple with chopsticks.
It ends with a "-세요", so it's polite. The only difference with my answer (which turns out to be wrong) and that with the correct one is the word "please" that I placed at the beginning of the sentence since it's polite. I hope this would be resolved and in the future answers similar to mine would be accepted as correct.