Final answer:
Alfred Stieglitz's belief that photography should reflect its unique qualities as an art form is closely associated with Pictorialism.
Step-by-step explanation:
Alfred Stieglitz asserted that for photography to be an art, it should be true to its own nature. This concept is closely associated with c) Pictorialism, which was part of the Photo-Secession movement. Stieglitz and his contemporaries in this movement believed that photographs should emphasize the unique qualities of the medium, going beyond simply mimicking paintings. Pictorialists manipulated photo materials to create artistic effects and to express the medium’s potential for originality.