Explanation: Evaporation happens when a liquid substance becomes a gas. When water is heated, it evaporates. The molecules move and vibrate so quickly that they escape into the atmosphere as molecules of water vapor (Dunn,1993).
        
                    
             
        
        
        
(c) is the correct choice.
El Nino (a), Earth's orbit (b), and solar energy output (d) are all "natural" occurrences.  You can't do a thing aboutum.
Fossil fuels ... or, more precisely, humanity's use of vast quantities of fossil fuels as a convenient source of huge quantities of energy ... and the subsequent increase of Carbon Dioxide in the planet's atmosphere, is not the result of "natural" processes.  It's the result of human efforts to <em>alter and control</em> Nature, through <em>artificial</em> processes.
 
        
             
        
        
        
<span>They are used to measure and map effluent and pollution discharges from factories and sewerage plants, and the movement of sand around harbours, rivers and bays. Radioactive materials used for such purposes have short half-lives and decay to background levels within days.</span>
        
                    
             
        
        
        
Scientists conduct experiments in order to prove a theory or a prediction they have or contradict it, so that then they can write down their results to study them.
        
             
        
        
        
Its very dense. Hey, are you homeschooled?