From studies and research, I believe the proper question would be:
"How do the animals satisfy their need for water?" or "How long do the animals live?"
Explanation 1:
When studying the desert, asking "Can you buy the animals in pet stores?" is not going to help you find information about the desert because it is not a question to get information about the desert, only information if you just buy it at your local pet shop.
Explanation 2:
Asking "How many offspring do the animals have?" does help us learn about animals, but we are trying to find information on the structure of the desert in which the animals live in. We are not looking for how many children the animals will have because it doesn't fully relate to the question we would be asking. 
Side Note: Offsprings mean children.
            <em>Hope this helps!</em>
<em>       ~Hocus Pocus</em>
 
 
        
             
        
        
        
Answer:
Elements that are found in the same horizontal row (belong to the same period) in the periodic table, e.g. Fluorine and Neon both have the same energy level of 2.
<em>Note: The question does not specify any two elements.</em>
Explanation:
The modern periodic table is organized into eight vertical columns known as groups and seven horizontal rows known as periods. The atomic number ( number of protons in the nucleus) of elements increases when moving across the periodic table from left to right. The horizontal rows or periods represents an energy levels or the number of electron shells in an element. Energy levels (also called electron shells) are fixed distances from the nucleus of an atom where electrons may be found. Elements belonging to the same period have the same number of energy level or shells. For example, the elements belonging to Period 2 include lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine and neon. These all have the same number of energy level of 2.
 
        
             
        
        
        
B. bacteria that convert ammonia into nitrites and nitrates are found in the soil  
This statement best demonstrates a way that the geo-sphere is involved in the nitrogen cycle.
A nitrogen cycle is defined as the movement of nitrogen between the atmosphere, biosphere, and geo-sphere in different forms. Ammonia is converted to nitrates by nitrifying bacteria in the soil. Then the plants absorb these nitrates from the soil and use these to build up proteins.
 
        
                    
             
        
        
        
The answer is b because that's the only place where the leaf can be water to go through transpiration and the water cycle