ANS:A - number of electrons.

In an oxidation process, there is typically an increase in the oxidation number of the atoms involved. Therefore, the correct statement is: An oxidation process is accompanied by an increase in the oxidation number. So, the options (a) and (b) are incorrect. Regarding option (c), the number of ions may or may not decrease during an oxidation process, depending on the specific reaction and conditions. Therefore, the correct answer is: An oxidation process is accompanied by an increase in the oxidation number.