Hydrochloric acid in gastric juice helps to make jokes.

A. The aqueous solution of carbon dioxide is acidic. If carbon dioxide produced by metabolism is not discharged in time, it will enhance the acidity of blood and reduce the pH value of blood.

B, PVC is toxic and cannot be used for food packaging, wrong;

C, vegetables and fruits are rich in vitamins, correct;

D, a small amount of hydrochloric acid in gastric juice can help digestion and correction;

So choose B.