C. reinhardtii is a species of unicellular green algae that primarily produce energy for growth throughout photosynthesis. However, when necessary, they can also produce energy from a carbon source, which allows them to grow in total darkness. A scientist grows a population of this algae in the dark and finds that after 600 generations, the algae population now grows better int he dark than in the light. Which statement best explains what has happened to the cells in the algae population? A. The cells that were better adapted to growing in the dark reproduced more.
B. The cells that were better adapted to growing in the light got smaller in size.
C. They became contaminated with a species of algae that grow only in the dark.

D. They evolved into a different species that can grow only in the dark.