Which of the following pa is the narrowest pa of ureter during its course to the bladder?

The ureter is a retroperitoneal organ that transpos urine that is propelled by peristaltic waves from the kidney to the urinary bladder. The adult ureter is about 30cm long. Areas of relative narrowing are found,At the ureteropelvic junctionwhere the ureter crosses over the iliac vesselswhere it courses through the bladder wall.Also know:In males, the ureter courses posterior and medial to the ductus deferens and anterior to the seminal vesicle. In females, the ureter courses lateral to the cervix, where the ureter courses inferior to the uterine aery.Ref: Tanagho E.A. (2008). Chapter 1. Anatomy of the Genitourinary Tract. In E.A. Tanagho, J.W. McAninch (Eds), Smith's General Urology, 17e.