Sperms are stored in which part of the reproductive system in male cockroaches

The correct option is Seminal vesicles.

To understand why this is the correct answer, let's break down the structure and functions of the components of the male reproductive system in a cockroach:
1. Testes: A pair of three-lobed testes is located dorsolaterally in the 4^th to 6^th abdominal segments. Their primary function is the production of sperms.
2. Vas deferens: From each testis, a thin duct called the vas deferens arises. The vasa deferentia run posteriorly and conduct the sperms from the testes down to the seminal vesicles.
3. Seminal vesicles: These are sac-like structures where the sperms, received from the vas deferens, are stored. Inside the seminal vesicles, the sperms are glued together in bundles called spermatophores, preparing them for discharge during copulation.
4. Mushroom glands: Located in the 6^th to 7^th abdominal segments, these function as accessory reproductive glands. They secrete a nourishing fluid but do not serve as storage sites for the sperms.

Therefore, the site of sperm storage in male cockroaches is the seminal vesicles.