Answer;
-Simple squamous epithelium
Explanation;
-Simple squamous epithelium is the single layer of thin, flat cells that line body surfaces which are not exposed substantially abrasive forces. The primary function of the columnar cell is that secretion and absorption simple squamous epithelium a single layer flat scale shaped cells.
-Simple squamous epithelium lines the air sacs, or alveoli, of the lungs. The alveoli are sites where air is exchanged in the lungs. Simple squamous epithelial cells in the alveoli allow oxygen from the air to enter the blood in the capillaries of the lung.
The answer is to your question is A
Placenta
It also does not allow the maternal and fetal bloodstreams to mix
Answer:
The last one: dinosaur footprints preserved in mud turned to rock
Fossils have to be physical remains of an animal.
Hope this helps!
