Some examples of limiting factors are biotic, like food, and mates. Limiting factors can affect the populations of both plant and animal species. An invasive species is an organism that is not indigenous, or native, to a particular area.
I think its C.
I hope this helps and please do correct me if im wrong.
The placenta and the umbilical cord
Pull Of Gravity , that is why you have weight or else without gravitational pull you only have mass hence the equation w = mg