The answer to this is rolling friction
The correct answer is hydronephrosis. Distention means being enlarged or swollen due to internal pressure. In this case, the internal pressure would be urine collecting in the kidney. This occurs when the urine is unable to drain from the kidney to the bladder due to an obstruction. Contrary to common belief, hydronephrosis is not a disease itself, but is instead is the result of a disease.
Embryo should be the answer
B. An ecosystem in which plant roots are submerged during parts of the years
Very powerful microscopes were needed before cells could be observed in detail
