Final answer:
Many viewers were disturbed by the bareness and unconventional composition of Édouard Manet's Luncheon on the Grass, when the painting was first exhibited. So, the option is C.
Step-by-step explanation:
The aspects of Édouard Manet's Luncheon on the Grass that bothered many viewers when the painting was first exhibited were primarily the bareness and unconventional composition. At the time of its debut, the painting caused an impropriety because it featured a bold depiction of a undress woman sitting alongside two fully clothed men, in a contemporary setting that suggested ordinary people rather than mythological subjects or deities.
This broke away from the traditional representations of the undress form in art, and the lack of interaction among the figures, combined with the woman's direct gaze at the viewer, intensified the controversy. Manet's work, including Luncheon on the Grass and Olympia, challenged the artistic norms of the time and paved the way for modern art. His use of bold brushstrokes and flattened perspective also contributed to the break from traditional art standards, which generally favored smooth, more detailed finishes and classical subject matter.
Therefore, C is the correct option.