Increasing the concentration of substances in a chemical reaction will
increase reaction rate
decrease reaction rate
have no effect on reaction rate

Option (a) is the correct answer.

Explanation:

When we increase the concentration of substances in a chemical reaction then it means there are more number of molecules present in a reaction.

Hence, when these molecules will interact with each other then there will occur more number of collisions. As a result, kinetic energy of molecules will increase and this leads to increase in rate of chemical reaction.

Thus, we can conclude that increasing the concentration of substances in a chemical reaction will increase reaction rate.