Consider the below statements and identify the correct answer. Statement-I: If a substance loses oxygen during a reaction, it is said to be reduced. Statement-II: If a substance gains hydrogen during a reaction, it is said to be reduced.

In redox reactions, statement I is correct because the loss of oxygen by a substance is a form of reduction, and statement II is also correct because the gain of hydrogen by a substance is another form of reduction. Both criteria—losing oxygen or gaining hydrogen—describe reduction in a chemical reaction.