The correct answer is option 3: proteins. Enzymes are a type of protein that function as biological catalysts. They speed up chemical reactions in living organisms by lowering the activation energy required for the reactions to occur. Proteins are large complex molecules made of amino acids that are linked together in a specific sequence. Enzymes have a very specific structure that allows them to bind to specific substrates and facilitate the chemical reactions.

Option 1, carbohydrates, is incorrect because enzymes are not carbohydrates. Carbohydrates are a class of biomolecules that serve as a source of energy in living organisms.

Option 2, lipids, is incorrect because enzymes are not lipids. Lipids are another class of biomolecules that include fats and oils and are primarily involved in energy storage and insulation.

Option 4, amino acids, is incorrect because while enzymes are made of amino acids, they are not themselves amino acids. Enzymes are proteins that are composed of chains of amino acids.

So, the correct answer is option 3: proteins.