The correct answer is endothelium.
The endothelium is a thin layer of single-layered, squamous cells that can be found in the lumen of blood vessels, on the interior surfaces of the heart chambers, in the glomerulus of the kidney...The main function of endothelium is barrier function when it acts as a semi-selective barrier between the lumen of the vessels and surrounding tissue, and thus, controls the passage of materials. The endothelium is also included in functions such as fluid filtration in the kidneys, the control of blood pressure (vasodilatation and vasoconstriction), inflammation.
CGCUUAACG -mRNA is that what you’re asking ??
True because of the fact that index fossils help correlate and date from its origin and date of existence. basically, it is a fossil that is kept and annalized.