The amount of light that passes through the lens and reaches the digital sensor is called exposure.
So, exposure determines how much light or darkness will get to the sensor, and thus how light or dark the image will be when you take a photo. There are settings that are responsible for this: ISO, aperture, and shutter speed - which together are called "the exposure triangle."
The majority of operas were made around the Orpheus legend. The most famous of these was the earliest performance of Monteverdi's "L'Orfeo." in 1607. Nevertheless, I highly believe the answer to this is B. Orpheus.
