On remarkable realization associated with the discovery of sea floor spreading was that

Compared to continents, the crustal floor of the oceans is very young.

Explanation:

This is true because oceanic crust is constantly being recycled. It is subducted into the mantle where it is destroyed and new oceanic crust is produced at mid-oceanic ridges, so it is younger than the continents.

answer; the tunica intima also called tunica interna, consists of elastic fibers,connective tissue and smooth muscle cells;