Look at the diagram of Woese’s modern system of classification.
Kingdom
Phylum
Class
Order
Family
Genus
Species

Which level is missing on top of the diagram?

Linnaeus
Domain
Aristotle
Family

b c a d mark me

that is wrong, its not thymus.

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.