The correct answer for the given question above would be option A. The two organ systems that regulate homeostasis in our bodies are nervous and endocrine. The nervous system is responsible in the coordination of different systems in the body, including the voluntary and involuntary function. Whereas, the endocrine system, along with the nervous system is responsible for the regulation of different hormones that are responsible for different functions in the body.
The answer is:
A) Cells are the basic unit of life.
B ecosystem. They include abiotic factors and biotic factors.
Answer: crossing over allows for genetic variation
Explanation:
crossing over is the exchange of genes between two chromosomes which ends up resulting in non-identical chromatids that comprise the genetic material of gametes (sperm and eggs).
Basically crossing over makes the chromatids that are held together by a centromere, no longer identical to eachother which creates genetic variation.