D because they are complete systems
Answer:
The environment that it lives in has not changed much, therefor there is no need for evolution to take place.
Explanation:
Water molecules are not found in a dna molecule.
A variation is a reference to the differences or deviations, such as the structure and form, as for crossing over is the exchange of genetic material between the non-sister chromatids of the homologous chromosomes during meiosis.
I think it's <span>a=F/m ; F=m/a=1200 kg x 3.0 m/s^2 = 3600 N</span>
