The answer for this question would be Integument, digestive, respiratory and urogenital.
The largest system that contact with the external environment would be integument and digestive. That makes two system has normal flora of microbes and not sterile like the other systems. Normal flora of microbes will prevent the pathogen microbe grows so it gives some benefit.
I think the correct answer from the choices listed above is option D. Human height is determined by several genes located on different chromosomes which is an example of a polygenic trait. These traits are being controlled by more than one gene. Hope this answers the question.
If I’m not mistaking it’s the 2nd one plant cell
its the circulatory system
The gravitational force between two rolling balls depends on their masses and which other factor?
Answer: C) Their separation "100% sure
Good luck and Have a nice Benevolent Day! :)
