Pick from:
a). vision
b). words
c). sound
d). Light
e). waves
f). Acids
g). language
h). scent

Fact 1: Echinoderms use pheromones to communicate with each other. Fact 2: Scent marks contain molecules called pheromones. Given the two facts above, what do echinoderms use to communicate?
Answer:
h).