Answer the following question: Fact 1: Some insects can use their antennae to detect sound. Fact 2: An insect's head has two feelers, or antennae. Given the two facts above, what can some insects use their feelers to detect?

Pick from:
[1]. kale;
[2]. noise;
[3]. water vapor;
[4]. tremors;
[5]. waves;
[6]. vibrate;
[7]. air;
[8]. sound;
Answer:
[8].