In a science experiment, equal-sized populations of two species of earthworms are placed in a terrarium filled with soil. Abiotic factors such as temperature and water supply are kept constant in the terrarium, as is food in the form of bread scraps. The population of each species is observed and counted each day. In agreement with the competitive exclusion principle, what is the MOST LIKELY outcome of the experiment over time? A. Only one population will thrive; the other population will decrease to zero. B. Both populations will reach the same size, which is the carrying capacity of the terrarium for earthworms. C. One population will be about twice the size of the other. D. Both populations will reach the same size, which is about half the carrying capacity of the terrarium for earthworms.

According to the competitive exclusion principle if the two species are dependent upon the same ecological niche, then the one which is more superior and stronger than the other will survive and the other one will reduce in size of the population or may extinct.

According to the given situation, the two species of earthworms are subjected to same treatment of abiotic factors such as temperature, water supply. The food was in the form of bread scraps. The more strong and competitive species is likely to thrive the food and will survive the other species population will decrease.