Max Wants to Start a Farm to Grow Mussels

Short Answer

Max wants to start a farm to grow mussels. He needs to determine the best environment for growing them. He is going to try two different amounts of salt in the water (salinity) and three different water temperatures. For his experiment he has
18 aquariums, each with 20 mussels. He wants to see which environment produces the largest mussels.
-Identify the subjects.