Our eyes perceive colors because of differences in which of the following properties of light? a)
Wavelength

b)
Intensity

c)
Source

d)
Angle

The properties of light is option a wavelength.

It is the distance between the points of two consecutive waves. It is usually denoted by the Greek letter lambda (λ), and it is equal to the speed (v) of a wave train in a medium divided by its frequency (f): λ = v/f.

So based on the above information, the a option is correct.

Learn more about the light here: link

adding a(n) to an electric circuit would increase the magnetic field around a wire;

b. solenoid

a solenoid is a type of electromagnet whose purpose is to generate a controlled magnetic field.

if the purpose of the solenoid is instead to impede changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet.