Direction and Displacement would be your answer.
        
                    
             
        
        
        
Answer:
the distance between successive crests of a wave, especially points in a sound wave or electromagnetic wave.
Explanation:
Please tell me if it helps
 
        
                    
             
        
        
        
Helper T cells become activated by interacting with antigen presenting cells. and the second blank space is either cytotoxic t cells or B cells
        
             
        
        
        
Explanation:
to be honest I'm not sure how to do