Bees see the colors yellow and blue, but not red. Flowers that need to be pollinated by bees are mostly yellow of blue. What type of evolution is that?

Natural Selection

Explanation:

In natural selection process of evolution, traits that are essential for an individual to be fit enough to survive under environmental stress become dominant.

Since the flowers are of blue or yellow color, it is essential for a bee to be able enough to perceive the blue and yellow color. Hence, the eyes of bee with time have evolved to perceive these two color so that they can pollinate flower.