**Core Concept**
In vitro fertilization (IVF) involves the union of a single oocyte with a sperm, bypassing natural fertilization processes. Sperm capacitation, acrosome reaction, and oocyte activation are critical steps in successful fertilization.

**Why the Correct Answer is Right**
For IVF to be successful, a single sperm is sufficient to fertilize an oocyte. This process is made possible by the presence of the oocyte's zona pellucida, which binds to the sperm and facilitates its entry into the oocyte. The sperm's acrosome reaction is essential for breaching the zona pellucida, while the oocyte's cortical reaction and subsequent activation are crucial for fertilization and subsequent embryonic development.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because multiple sperm are not required for IVF. In fact, excessive sperm presence can lead to polyspermy, a condition where multiple sperm fertilize the same oocyte.

**Option B:** This option is incorrect because it suggests a specific number of sperm, which is not supported by scientific evidence. The number of sperm required for IVF is not a critical factor in determining fertilization success.

**Option C:** This option implies that multiple sperm are necessary for fertilization, which is incorrect. In IVF, a single sperm is sufficient to fertilize an oocyte.

**Clinical Pearl / High-Yield Fact**
In IVF, a single sperm is sufficient for fertilization, making it an efficient and effective reproductive technology.

**Correct Answer: C. One sperm is sufficient for fertilization in IVF.**