Trigone of Bladder is derived from:

Ans. B. MesodermDuring the fourth to seventh weeks of development the cloaca divides into the urogenital sinus anteriorly and the anal canal posteriorly. The urorectal septum is a layer of mesoderm between the primitive anal canal and the urogenital sinus. Urogenital sinus forms the urinary bladder. During differentiation of the cloaca, the caudal portions of the mesonephric ducts are absorbed into the wall of the urinary bladder. The mucosa of the bladder formed by incorporation of the ducts (the trigone of the bladder) is mesodermal.