Answer:
because they need foodi think
I think its C. global warming
because the other one directly threats aquatic bio diversity while global warming doesn't just affect aquatic biodiversity
B.The embryo attaches to the mother
The renal medulla is made for the most part out of gathering channels and the nephron circles. You won't perceive any glomeruli in the medulla, as they are restricted to the cortex. This makes the renal cortex and renal medulla effortlessly recognizable.