It some back to earth since gravity pulls it down
        
             
        
        
        
Answer:
B. a substance that can donate an H+ ion
Explanation:
 
        
                    
             
        
        
        
Cannabinoid receptors, located throughout the body, are part of the Endocannabinoid system which is involved in a variety of physiological processes including appetite, pain-sensation, mood, and memory.[1]
Cannabinoid receptors are of a class of cell membrane receptors under the G protein-coupled receptor superfamily. As is typical of G protein-coupled receptors, the cannabinoid receptors contain seven transmembrane spanning domains.[5] Cannabinoid receptors are activated by three major groups of ligands: endocannabinoids, produced by the mammillary body; plant cannabinoids (such as Cannabidiol, produced by the cannabis plant); and synthetic cannabinoids (such as HU-210). All of the endocannabinoids and plant cannabinoids are lipophilic, such as fat soluble compounds.
 
        
             
        
        
        
100,000 years ago is your answer
        
             
        
        
        
Ovulation is the process in which eggs are released from the ovary.