**Core Concept**
Severe male factor infertility is often associated with oligospermia (low sperm count), asthenospermia (low sperm motility), or teratospermia (abnormal sperm morphology). The treatment of choice for severe male factor infertility involves assisted reproductive technologies (ART) that bypass natural conception.

**Why the Correct Answer is Right**
ICSI (Intracytoplasmic Sperm Injection) is a type of ART where a single sperm is injected directly into the egg to facilitate fertilization. This technique is particularly useful for men with severe oligospermia, as it allows for the selection of a single healthy sperm for fertilization. The success of ICSI is largely dependent on the quality of the sperm, making it a preferred option for men with severe male factor infertility.

**Why Each Wrong Option is Incorrect**
* **Option A:** IVF (In Vitro Fertilization) involves fertilizing multiple eggs with sperm in a laboratory dish. While IVF can be effective for male factor infertility, it is not the most suitable option for severe cases where sperm count is extremely low.
* **Option B:** IUI (Intrauterine Insemination) involves inserting sperm directly into the uterus, bypassing the cervix. However, IUI is not effective for severe male factor infertility, as it does not address the underlying issue of low sperm count or poor sperm quality.
* **Option C:** Vasectomy reversal is a surgical procedure that reconnects the vas deferens after a vasectomy. While it can restore fertility in some cases, it is not a suitable option for severe male factor infertility, as it does not address underlying issues of oligospermia or asthenospermia.

**Clinical Pearl / High-Yield Fact**
For men with severe male factor infertility, ICSI is often the most effective treatment option, but it requires a minimum of 5-10 million sperm per milliliter to be successful. This highlights the importance of thorough semen analysis and careful patient selection in the treatment of severe male factor infertility.

**Correct Answer:** C.