You might put harmful toxins in the beach or into the ocean which would kill wildlife 
        
             
        
        
        
False because the third line of defense is specific by identifying the foreign antigen and activating the antibodies that can bind to the invaders and eliminating the spread
        
                    
             
        
        
        
The correct answer is 'If molecules are small enough, then they can pass through the semipermeable membrane because they can cross the semipermeable membrane from their small pores or openings'.
The semipermeable membrane is permeable to few molecules, and the smaller molecules pass through the molecules from small pores present in the semipermeable membrane. The size of the big molecules are large, so, they cannot cross through semipermeable membrane. 
 
        
                    
             
        
        
        
HIV directly attacks CD4 helper lymphocytes directly. (D)