Explanation:
It happens when the moon is in the earth's shadow
And sun moon and earth is completely aligned 
 
        
                    
             
        
        
        
Answer: population increases by 15
Explanation:
The population growth will be calculated by adding the Natural Increase in population plus the Net In-Migration. This will be:
Natural increase = Birth - Death rate 
= 35 - 7
= 28
Net-In-Migration = Immigration - Emigration
= 4 - 17
= -13
Therefore, population growth will be:
= 28 - 13
= 15
Therefore, population increases by 15
 
        
                    
             
        
        
        
Answer:
The correct answer would be d. thymus.
The thymus is a specialized lymphoid organ of an immune system.
It serves as the site for training and maturation of T-lymphocytes or T cells.  
It is composed two identical lobes each containing outer region termed as cortex and inner region termed as medulla.
T-cells are first trained and selected in the cortex region via positive selection. In this, T cells which are able to bind to foreign antigens are selected and rest are degraded.
The selected T cells then move in the medulla region where they are selected by negative selection. In this, the T cells which binds to self-antigens are degraded and rest survive to become functional T cells.
 
        
             
        
        
        
I think the answer is A. vacuole