Final answer:
Marcel Duchamp's 'Fountain' is a seminal 1917 work that redefined modern art by presenting a urinal as a sculpture, laying the groundwork for future art movements.
Step-by-step explanation:
Marcel Duchamp's Fountain, created in 1917, is an icon in modern art, known for its radical challenge to traditional notions of sculpture. This work consists of a porcelain urinal signed "R. Mutt" and submitted to the Society of Independent Artists exhibition, where it was initially rejected. Fountain is amongst Duchamp's readymades, ordinary manufactured objects that the artist selected and modified, repositioning them as art simply through their selection and presentation. The piece was photographed by Alfred Stieglitz, helping to circulate the image and concept, and despite initial scorn, it has become an influential modernist work, even being celebrated as 'the most influential work of modern art' by the Turner Prize committee in 2004. Duchamp's challenge with Fountain opened the door for future avant-garde movements including Pop Art, Fluxus, and Conceptual Art.