Answer : The correct option is, (B) occur when oxygen is gained or electrons are lost.
Explanation :
Redox reaction is a type of reaction in which the oxidation and reduction reaction takes place simultaneously.
Oxidation reaction : It is the reaction in which a substance looses its electrons or we can say that the oxidation reaction occurs when the oxygen is gained. In this, the oxidation state increases.
Reduction reaction : It is the reaction in which a substance gains electrons or we can say that the reduction reaction occurs when the oxygen is lost. In this, the oxidation state decreases.
Hence, the correct option is, (B) occur when oxygen is gained or electrons are lost.
