**Core Concept**
The major contribution to semen is derived from the seminal vesicles, prostate gland, and bulbourethral glands, but the seminal vesicles contribute the largest volume of fluid.

**Why the Correct Answer is Right**
The seminal vesicles produce a significant amount of fructose, which serves as an energy source for spermatozoa, and also contribute a high volume of clear, alkaline fluid that neutralizes the acidic environment of the vagina. This alkaline environment is crucial for sperm survival and motility. The seminal vesicles secrete the enzyme coagulase, which helps in the coagulation of semen.

**Why Each Wrong Option is Incorrect**
* **Option A:** The prostate gland contributes a smaller volume of fluid compared to the seminal vesicles but is crucial for the coagulation of semen through the secretion of prostatic fluid. It does not make the major contribution to semen.
* **Option B:** The bulbourethral glands secrete a small amount of clear fluid, but this is not the major contribution to semen.
* **Option D:** The epididymis is involved in sperm maturation and storage but does not contribute to the semen.

**Clinical Pearl / High-Yield Fact**
The seminal vesicles are a common site for the development of seminal vesiculitis, which can be caused by various infections, including sexually transmitted infections.

**Correct Answer:** C.