Consider the following houses: 1. Christie's 2. Osian's 3. Sotheby's Which of the above is/are' auctioneer/ auctioneers ?

Christie’s and Sotheby’s are two of the world’s foremost auction houses and have regularly conducted auctions of Indian and international art, demonstrating their roles as auctioneers [1]. Osian’s (Osian’s Connoisseurs of Art), headquartered in Mumbai, also operated as an auction house in India, holding regular sales of modern, contemporary and other art categories before its financial troubles were reported; it has been described in sources as one of the Mumbai-based auction houses running auctions domestically. Thus all three — Christie's, Osian's and Sotheby's — have functioned as auctioneers, making option 4 (1, 2 and 3) the correct choice.

Sources

1. [1] https://www.reuters.com/article/economy/feature-india-contemporary-art-in-demand-as-country-booms-idUSDEL244814/