Which of the following is a certification mark employed on metals in India to assure their quality?

Hallmark

While buying many commodities, on the cover, you might have seen a logo with the letters ISI, Agmark, Hallmark. These logos and certification help consumers get assured of quality while purchasing the goods and services. The organisations that monitor and issue these certificates allow producers to use their logos provided they follow certain quality standards. ISI mark is a standard-compliance mark for "Industrial products", Agmark is a certification mark employed in "Agricultural products", whereas Hallmark guarantees a certain purity of "Metal".