<span><em><u>B. species.</u></em>
</span>
The organismic hierarchy of organism comes from the highest and lowest order as the following; 
<span>1.    D Domain</span> <span><span>
2.    </span>K Kingdom</span> <span><span>
3.    </span>P Phylum</span> <span><span>
4.    </span>C Class</span> 
<span>5.    O Order</span> <span><span>
6.    </span>F Family</span> <span><span>
7.    </span>G Genus</span> 
<span>8.    S Species</span> 
This hierarchy and order helped many taxonomist to determine and classify organisms by a variety of criteria. And it seems that <em>species </em>can breed the same fertile offspring.
        
                    
             
        
        
        
Answer:
Both algae and phytoplankton
Explanation:
In the aquatic ecosystems, both algae and phytoplankton are producers and on land, plants are the primary producers. 
The primary producers provides food for the whole ecosystem. 
- During photosynthesis these producers are able to take up inorganic compounds and synthesize organic molecules. 
- They use carbon dioxide and water in the presence of sunlight to produce glucose and oxygen gas
- The glucose is the food on which the ecosystem depends on 
- Algae and phytoplankton produces food this way too. 
 
        
             
        
        
        
Answer:
Differentiation
Explanation:
Differentiation - it is referred to that alteration in less specialized cells which undergoes the maturation process to develop in more distinct form and function. The process undergoes the transmission of the single zygote into a cluster of tissues.
It also refers to the process that initiates during prenatal development. During this process maturation of cells takes place i.e. some cells become distinct in cells, some in legs, etc.