Answer: Option (a) is the correct answer.
Explanation:
A chemical reaction is the reaction that involves gain and loss of electrons due to which there is formation of new compounds or products.
Foe example, [tex]HCl + NaOH \rightarrow NaCl + H_{2}O[/tex]
That is, in chemical reactions change in oxidation state of reactants occur.
Hence, we can conclude that out of the given options electrons participates in chemical reactions.