Answer:
b. Organisms in each ecological system have evolved in that system and have adaptations suited for that environment.
Step-by-step explanation:
The abiotic factors of one ecosystem differ from that of the other. A forest ecosystem mostly has enough of rainfall, suitable temperatures, soil fertility and availability of nutrients to support the growth of numerous life forms. On the other hand, a desert ecosystem is characterized by water scarcity, extremes of temperatures, infertile soil, and other unfavorable abiotic conditions that allow only certain plant and animal species to survive there.
Therefore, life forms are adapted to the surroundings and two ecosystems with different abiotic conditions will have different species of plants and animals.