A male cardinal’s red color is an example of a trait affected by natural selection. The females of the species choose mates based on the vibrant colors of the males’ feathers. If females begin using different criteria than feather color when they choose mates, what would most likely happen to the color of the male cardinals over time?
increased variation in the shades of red because there is no advantage in one specific color
increased variation in the shades of red because the cardinals try different ways to impress the females
decreased variation in the shades of red over time because no form of the trait is advantageous
decreased variation in the shades of red after a single generation

decreased variation in the shades of red over time because no form of the trait is advantageous

Explanation:

Natural selection tends to favor those organisms which are better adapted to live in an environment. These organisms are able to survive and pass on their characteristics to their offsprings.

The red colour of the male cardinal's was selected by natural selection and hence this colour was abundant. If the females choose some other criteria for mating with males, then natural selection will no longer favor the red colour and hence there will be a decrease in the variations of red coloiur.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.