After many uses, your teakettle may develop some deposits on the inside of the kettle. these deposits are a result of:

solutes dissolving in a solution

solutes becoming un-dissolved from a solution

solvents dissolving in a solution

solutions forming from solutes and solvents

i think it's b., am i correct?

edit:
never mind, i don't need anymore. i was right, it was b. i'm happy i got it right on my own, but still disappointed that no one tried to : (

The correct answer is the second option.  These deposits are a result of solutes becoming un-dissolved from a solution. These solutes are from the water or liquid that you are boiling in the kettle. As you boil a liquid mixture, it is possible that some of the solutes would precipitate because the solubility of such solute is lowered due to the increase in the temperature. Most solubility of solid solutes are related to temperature inversely. So, as the temperature increases, the solubility would decrease. Solubility is the amount of a solute  that can be completely dissolved in a certain amount of solvent.