Which thin-walled blood vessels lack muscular walls? veins arterioles capillaries arteries

Answer;

Capillaries

Explanation;Capillaries are blood vessels that don have the muscular or the elastic tissue of other blood vessels.Capillaries have single celled wall to help substances be transported through different tissues in the body of an organisms. They are smaller than any other blood vessels. The important function of circulation takes place in the capillaries; materials are exchanged between circulation and cells.  they are sites of the transfer of oxygen and other nutrients from the bloodstream to other tissues, and also collect carbon dioxide and waste materials from the cells.