The three layers of smooth muscle that includes mucosa. innermost tunic of a ureter; formed by transitional epithelium that is both stretchable and impermeable to the passage of urine; external to the transitional epithelium is the lamina propria, composed of dense irregular connective tissue The correct answer is 2 Solution The three layers of smooth muscle that includes mucosa. innermost tunic of a ureter; formed by transitional epithelium that is both stretchable and impermeable to the passage of urine; external to the transitional epithelium is the lamina propria, composed of dense irregular connective tissue The correct answer is 2.