Which of the following is selenium containing enzyme?: (A) Xanthine oxidase, (B) Glutathione peroxidase, (C) Superoxide dismutase, (D) Lysyl oxidase
Answer is B. Other examples of Selenium containing enzymes are:(Selenocysteine is a part of these enzymes)

Thioredoxin reductase
Deiodinase
Glutathione peroxidase