C) Milk boils at about 212°F (100°C). 
        
             
        
        
        
The answer is (4). You may recall the term "radiometric dating," which refers to the dating of old artifacts by measuring proportions of certain radioactive isotopes they contain and making calculations based on their estimated half-lives. Geological formations are dated in this way.
        
             
        
        
        
An electron has a relative mass of 0, whilst an alpha particle has a relative mass of 4
An electron has a relative mass of 0, whilst a proton has a relative mass of 1
A neutron has a relative mass of 1, whilst an alpha particle has a relative mass of 4
A neutron has a relative mass of 1, and a proton also has a relative mass of 1