Fact 1: Some arthropods have special excretory structures.

Fact 2: Insects are the largest group of arthropods.

Given the two facts above, answer the question "what have special excretory structures sometimes?" with the following options: 
- h2o
 - fur seals
 - excretion
 - fungi
 - bees
 - insects
 - barnacles
 - clouds


 

      insects   