Reactions involve the gain or loss of oxygen or hydrogen by substances.

Statement A: Oxidation is the loss of oxygen and gain of hydrogen.

Statement B: Reduction is the loss of hydrogen and gain of oxygen.

Option 1 -> This would mean both definitions are correct, but they are actually reversed.

Option 2 -> Statement A is not correct as it reverses the definition of oxidation.

Option 3 -> Statement B is not correct as it reverses the definition of reduction.

Option 4 -> Both statements have reversed definitions of oxidation and reduction.

Hence, Option 4: Both statements A and B are incorrect -> The correct definitions are: Oxidation is the GAIN of oxygen or LOSS of hydrogen, while Reduction is the GAIN of hydrogen or LOSS of oxygen. Both statements have these definitions completely backwards. A helpful mnemonic is "OIL RIG" (Oxidation Is Loss of hydrogen, Reduction Is Gain of hydrogen) -> correct