Final answer:
MacConkey Agar contains lactose and peptones, which supply carbon to bacteria, aiding in differentiation and identification of enteric bacteria.
Step-by-step explanation:
The ingredients in MacConkey Agar (MAC) that supply carbon for bacterial growth include lactose and peptones. Lactose is a disaccharide that acts as a fermentable carbohydrate source, allowing differentiation between lactose fermenting and non-fermenting bacteria based on colony color change. Peptones, which are derived from animal proteins, provide a rich source of amino acids and nitrogen. Various enteric bacteria can metabolize these carbon sources, making MacConkey Agar a useful diagnostic tool in microbiology to distinguish between different types of bacteria based on their biochemical properties.