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

Fact 2: Each starfish arm is lined with tube feet.

Given the two facts above, answer the question "Where does a starfish have its water vascular system?" with the following options: 
- salt and water.
 - Chlorophyll
 - the environment
 - in its arms
 - on the rocks
 - in its eyes
 - Epidermis
 - in the ocean


 

    in its arms     