The best answer is A
Saltwater fish are hypotonic to their surroundings. This means their blood has a higher water concentration than the surrounding sea water.
Due to the fact that there is more salt and less water outside their bodies, there is a tendency to take in salt and lose water.
To counter this, salt water fish drink a lot of the sea water and urinate very little. Special cells in the gills actively eliminate salt at the cost of extra energy and these fishes do not absorb any salt from the water they drink.
Answer:
If the activity of osteclasts(which demineralize bone) exceeded osteoblast activity(production of new bone), then the bone's mineral content(and thus its mass) would decline, making it weaker.
I believe the correct response is that the student measurements were precise but not accurate.
So that others will know the results of the experiments.