Fact 1: Echinoderms have a unique water vascular system with tube feet.

Fact 2: Another group of echinoderms are the echinoids.

Given the two facts above, answer the question "Which has a unique water vascular system?" with the following options: 
- roots
 - trees
 - Conifers
 - Echinoids
 - fur seals
 - Most plants
 - ferns
 - bushes


 

    Echinoids     