Which of the following is a correct, concise definition of carbohydrate at a biochemical level?

Carbohydrates are organic molecules made of saccharide units, typically following the empirical formula (CH2O)n, serving roles in energy and structure.

Carbohydrates are inorganic salts of carbon that do not contain hydrogen or oxygen and are primarily used to store genetic information.

Carbohydrates are polymers of amino acids that constitute the primary structural material of membranes and are chemically identical to proteins.

Carbohydrates are molecules solely composed of hydrogen and nitrogen used exclusively for neurotransmission and are not found in plants.