Fact 1: Some insects can use their antennae to detect sound.

Fact 2: Sound waves are compressional waves.

Given the two facts above, answer the question "what do some insects use their antennae to detect?" with the following options: 
- members of their own species
 - spiders
 - heat and light
 - an area swollen with pus
 - compressional waves
 - density
 - h2o
 - electromagnetic energy


 

     compressional waves    