What method will speed up a chemical reaction? apply heat
avoid grinding the substance
decrease the concentration of the reactants

The correct  answer is "apply heat". A method that will speed up a chemical reaction is to apply heat. Energy is directly proportional to kinetic energy which is the energy of motion. Increasing the heat will promote the molecules to move faster therefore colliding more to the molecules in the system resulting to a faster reaction.

What are the options? i can you if you give them.

You would be correct, boiling water does disinfect contamination.    the property of disinfecting means to kill  germs, bacteria and other pathogens or contamination  that might cause an infection or cause a person to become sickly. a couple methods of disinfecting are using soap, other cleaning supplies or by simply "boiling" the contaminate.  the reason why boiling water disinfects certain attributes is because some cells cannot survive the heat and pressure.