Which of the following is a constituent of MacConkey agar?

Composition of MacConkey Agar : 1. Enzymatic digest of Gelatin, Casein and Animal tissue: provides nitrogen, vitamins, minerals and amino acids essential for growth. 2. Lactose: fermentable carbohydrate providing carbon and energy. 3. Bile Salts: selective agents and inhibit Gram positive organisms. 4. Crystal Violet:Gram positive bacteria are generally inhibited by crystal violet. 5. Sodium Chloride: supplies essential electrolytes for transpo and osmotic balance. 6. Neutral Red: pH indicator. Which is red in color at pH's below 6.8. When lactose is fermented, the pH of the medium decreases, changing the color of neutral red to pink 7. Agar : Solidifying agent