Which of the following is a drug containing two sulfhydryl groups in a molecule?

Dimercaprol(BAL) has two SH groups which binds to those metals which produce their toxicity by interacting with sulfhydryl containing enzymes in the body. It is indicated in poisoning by arsenic, mercury, gold, bismuth, nickel and copper. It is used as an adjuvant along with calcium disodium edentate in lead poisoning, adjuvant to penicillamine in copper poisoning and Wilsons disease. It is contraindicated in iron and cadmium poisoning, because the dimercaprol-Fe and Dimercaprol - Cd complex is itself toxic. Ref: Essentials of Medical Pharmacology, 5th Edition, Pages 812-4.