**Core Concept**
The implantation of the blastocyst is a critical process in early pregnancy, involving the attachment of the embryo to the uterine lining. This process is regulated by complex interactions between the blastocyst and the endometrium, involving hormonal, cellular, and molecular mechanisms.

**Why the Correct Answer is Right**
The blastocyst normally implants in the endometrium, specifically in the **lateral uterine wall**, between 6-10 days post-fertilization. This is facilitated by the secretion of **human chorionic gonadotropin (hCG)**, which maintains the corpus luteum, and **progesterone**, which prepares the endometrium for implantation. The endometrial glands and stroma provide a nutrient-rich environment for the implanting blastocyst.

**Why Each Wrong Option is Incorrect**
* **Option A:** The **ampulla of the fallopian tube** is the site of fertilization, not implantation. The zygote undergoes several cleavages before reaching the uterus.
* **Option B:** The **myometrium** is the muscular layer of the uterine wall, not the site of implantation. The endometrium, a layer above the myometrium, is where the blastocyst implants.
* **Option D:** The **cervix** is the lower, narrow part of the uterus that opens into the vagina. It is not involved in the implantation process.

**Clinical Pearl / High-Yield Fact**
Remember that **implantation failure** is a leading cause of infertility, and **endometrial receptivity** is critical for successful implantation. Factors affecting endometrial receptivity include hormonal imbalances, uterine anomalies, and autoimmune disorders.

**Correct Answer:** C.