An animals life in a desert is to survive, depending on the type of desert though, but I assume the most common desert, the hot/dry desert. Most animals are nocturnal, because it becomes cooler at night, and live underground during the day.
Explanation:
magnesium Hydroxide + Hydrochloric react together and give us magnesium chloride + water
Answer: B
Explanation: to have a control, and many samples to investigate and cover the differences and anseretics.
The controlled variable, I think.