Which vegetable contains a chemical called anthocyanin that turns pink/reddish in the presence of acid, turns purple when neutral and turns blue or green when mixed with alkaline substances?

Red cabbage

The correct answer is option 4. Red cabbage.

The vegetable that contains a chemical called anthocyanin, which exhibits the described color changes, is Red cabbage.

Red cabbage contains anthocyanin pigments that are sensitive to changes in pH. In acidic conditions, the anthocyanins appear pink/reddish. When the pH is neutral, they appear purple. In alkaline conditions, they turn blue or green. This property makes red cabbage a popular ingredient for demonstrating pH indicators in science experiments and culinary applications.