Environmental science is  a branch of biology focused on the study of the relationships of the natural world and the relationships between organisms and their environments. An example of environmental science is the study of the natural world and how it relates to recycling and mulching.
 
        
                    
             
        
        
        
My best guess would be c because b makes no since we as humans do not have photosynthesis and are considered living organisims, d is also wrong because the brain requires oxygen, and its not a because the brain is made of cells.
        
             
        
        
        
The correct answer is C. Tissue
Explanation:
In the diagram, x is between organ and cell level. This implies this level of organization is smaller than an organ but no as small as one cell. In this context, the most suitable term to add to this level is a tissue because these are structures composed of specialized cells, which shows this level encloses cells. Also, a group of tissues forms an organ; this implies the organ is the level that follows the tissue. Examples of this include muscle tissue composed of muscle cells and that is part of organs including the heart.
 
        
             
        
        
        
Answer:
B
Explanation:
Mitosis is used to grow (makes diploid)
Meiosis is used to make haploid gametes