positive feedback could be contractions(as painful as it may seem, its true) in child birth and the ripening of fruit.
negative feedback include the regulation of blood glucose levels and osmoregulation
<span>I believe the answer is C. Grasslands and forests do not have permafrost--present in tundra and taiga so A can be eliminated. B is not right because forests and grasslands definitely do not get TOO much rain, assuming they're not talking about tropical rain forests. </span>
Alright, so mass is a property of a physical body. During physical changes, such as acceleration, force, etc, the mass stays the same since we are not affecting its physical shape, just where it is physics wise. So yeah mass is conserved during a physical change.
(This is very confusing I'm bad at explaining things sorry)
