How can you tell if an element has been reduced? A. The number of its electrons has not changed in the reaction, B. It has a positive oxidation state in the product, C. It has more electrons in the product than in the reactant, D. It has fewer electrons in the product than in the reactant.​

C. It has more electrons in the product than in the reactant

Explanation:

A type of reaction is called REDOX or oxidation-reduction reaction. In this reaction, substances (element or compounds) involved are either oxidized or reduced. To be oxidized means that a substance has lost electrons and hence, have a positive oxidation state in the product side.

On the other hand, reduction means that the substance has gained or accepted electrons, and hence has a reduced oxidation state in the product side. In other words, a reduced element will have more electrons in the product than in the reactant.

For example, in the following equation:

A + B = A- + B+

A is said to be reduced because it has more electrons (1) in the product than in the reactant (0).