Answer:
must be mined from underground 
Please mark me as brainliest
 
        
             
        
        
        
The answer is natural killer cells.
Natural killer cells are a type of lymphocytes and they are important for the innate immune system. They recognise stressed cells much faster than other immune cells. Their response is rapid and usually only a few days after a viral infection. They also respond to <span>cancer cell </span>formation. While other immune cells can detect only those harmful cells that have specific markers on the surface of the cell membrane, natural killer cells can even detect those cells that miss markers for apoptosis.
        
             
        
        
        
Cells are the basic building blocks of life, which can join together to form tissues, while different groups of tissues join together to form organs. These organs are then connected together to form organ systems, such as the digestive system, which includes the stomach, esophagus, intestines and other organs.
        
             
        
        
        
Provided that there's no diagram, most molecules have particular areas on the molecules, called the "active area" that act as a lock to a particular substrate's molecular structure, providing the key. 
An enzyme's active area is only able to be "unlocked" by a certain substrate's "key".