Secretions of which one of the following structures does not help in…

The correct answer is Option (3) → Urethra

Option (1) Epididymis — Its secretions help in maturation and motility of sperms. The epididymis is a coiled duct along the back of each testis. Sperms are kept here and mature with the help of its secretion.

Option (2) Seminal vesicles — Its secretions help in maturation and motility of sperms. The seminal vesicles are accessory glands. Their secretion forms a large part of the seminal plasma, the fluid in which sperms swim.

Option (3) Urethra — Its secretions do not help in maturation and motility of sperms. The urethra starts at the urinary bladder and runs through the penis to the outside. It is only a common passage for urine and semen. The book does not list it among the structures whose secretions act on sperms.

Option (4) Prostate — Its secretions help in maturation and motility of sperms. The prostate is an accessory gland. Its secretion is another part of the seminal plasma that keeps the sperms active.

NCERT Extract:
Gametogenesis – “… Sperms released from the seminiferous tubules, are transported by the accessory ducts. Secretions of epididymis, vas deferens, seminal vesicle and prostate are essential for maturation and motility of sperms. The seminal plasma along with the sperms constitute the semen.”
The Male Reproductive System – “… 1a). These ducts store and transport the sperms from the testis to the outside through urethra.”