If one is missing the opsin which detects wavelengths of approximately 560 nm what color would they be unable to see?

As per the question the wavelength of color of light is given as 560 nm.

We are asked to determine the color corresponding to this wavelength.

The visible spectrum corresponds to the wavelength range of 380 nm to 750 nm.

The visible spectrum contains seven colors of light.

The green light corresponds to the wavelength range of 495 nm to 570 nm.

Hence the correct answer to this question will be green light.