Final answer:
Artists were very interested in optical color during the Impressionist period, from 1860 to 1890, which emphasized capturing fleeting moments with unique brushstrokes, light, and hues.
Step-by-step explanation:
During which of the following periods were artists very interested in the use of optical color? The Impressionist period, which took place from 1860 to 1890, saw an intense interest in the use of optical color. The Impressionists rejected the known art styles of the time and focused on the awareness of light and color, capturing fleeting moments in time, and painting an plain air with broad brushstrokes that conveyed the light, intensity, and hues of natural environments.
While movements such as Realism depicted the world with photo-like quality, capturing the lives and hardships of the working class, it was the Impressionist movement that emphasized the transient effects of light and color. Notable developments like the invention of paint tubes allowed artists to move outdoors and directly capture the scene before them, which led to a revolutionary use of light and color. This major shift in technique and approach is distinct and characteristic of the Impressionist movement.