Answer:
B. Fragments of Rock are squeezed and cemented together.
help with what? there is nothing to answer
If the inner lining of the air sacs neither thin nor highly vascularized, then it can be inferred that AIR SACS ARE CANNOT BE THE SITES OF GASEOUS EXCHANGE BETWEEN AIR AND BLOOD. Air sacs are generally lined with mucus and surrounded with blood capillaries.
In case of birds, air sacs play an important role in respiratory system.
The answer your looking for is B different patterns of gene expression
