Cloudy weather can do what to colors in a photograph?

make them deeper and more vibrant
make them duller and more faded
make them faded and more grey
make them more yellow

Make them deeper and more vibrant

Explanation:

    Unlike sunny days, on gray days clouds function as a large diffuser of sunlight. Making lighting much more uniform and shadows softer, generally making your photos softer, a softer light without "hard" shadows.

    You can shoot without fear, the light of cloudy days is great!

    Color temperature and white balance are very important here too

     Knowing how to set up the camera for cloudy days helps a lot in getting the perfect shot.

    The color of light is measured in Kelvin temperature. The lower the color temperature, the warmer the light, and vice versa. Higher temperature, more "cool" and bluish is the light.

    Cloudy days have a color temperature closer to bluish.