Crossing-over never occurs between genes. Hope this helped :)
If a population of rabbits is introduced to a population of dandelions the rabbits will end up eating all the dandelions
The answer to this is multicellular. Unicellular organisms' life processes all take place in the one cell which is their entire being - their entire existence - whereas multicellular organisms require specialized organs and organ systems to keep us alive.
Answer.
B. Multicellular