The correct answer is option 'D', which states that the capacitance of sperms takes place in the uterus. Let's understand why this is the correct answer.

- **Seminiferous tubules:** The seminiferous tubules are located in the testes and play a crucial role in the production of sperm through a process called spermatogenesis. Spermatogenesis involves the differentiation of spermatogonia (sperm precursor cells) into mature spermatozoa. Capacitance, which refers to the ability of sperm to fertilize an egg, does not occur in the seminiferous tubules.

- **Epididymis:** The epididymis is a long, coiled tube located on the posterior surface of each testis. It serves as a storage and maturation site for sperm. Here, sperm gain their motility and undergo changes in their membrane proteins, allowing them to interact with the female reproductive system during fertilization. Capacitance does not occur in the epididymis.

- **Vas deferens:** The vas deferens is a muscular tube that transports mature sperm from the epididymis to the ejaculatory duct. It does not play a role in the capacitance of sperms.

- **Uterus:** The uterus is a hollow, pear-shaped organ located in the female reproductive system. It is the site where the fertilized egg implants and develops into a fetus during pregnancy. Capacitance of sperms refers to the changes that occur in the sperm's membrane and its ability to fertilize an egg. This process primarily occurs in the female reproductive tract, specifically in the uterus and fallopian tubes.

In the uterus, the sperm undergoes a process called capacitation, which involves changes in its membrane structure and molecular composition. These changes allow the sperm to become more motile and acquire the ability to penetrate and fertilize the egg. Capacitation is facilitated by various factors present in the female reproductive tract, such as cervical mucus and uterine secretions.

Therefore, option 'D' is the correct answer as the capacitance of sperms takes place in the uterus.