Fact 1: Organisms that live in marine biomes must be adapted to the salt in the water.

Fact 2: Another name for salt is sodium.

Given the two facts above, answer the question "Organisms in a marine biome must be be adapted to what in the water?" with the following options: 
- mud
 - Nutrients
 - sodium
 - toxins
 - motion
 - sugar
 - energy
 - an anion


 

   sodium      