**Core Concept**
In an infertile woman with proliferative endometrial changes, the preferred hormone is one that supports follicular growth and ovulation. This is crucial for achieving a viable endometrium for potential implantation of an embryo.

**Why the Correct Answer is Right**
The preferred hormone in this scenario is progesterone. Progesterone is essential for preparing the endometrium for implantation of an embryo and maintaining pregnancy. In a proliferative phase, the endometrium is preparing for ovulation and potential implantation. Progesterone helps to differentiate the endometrium, making it receptive to implantation. It also plays a crucial role in maintaining the pregnancy by supporting the growth and development of the embryo.

**Why Each Wrong Option is Incorrect**
**Option A:** Estrogen is not the preferred hormone in this scenario. While estrogen is involved in the proliferation of the endometrium, progesterone is necessary for differentiation and preparation for implantation.

**Option B:** FSH (Follicle-Stimulating Hormone) is not a hormone that can be administered to support endometrial preparation for implantation. It is involved in the stimulation of follicular growth, but not in preparing the endometrium for implantation.

**Option C:** LH (Luteinizing Hormone) is involved in ovulation, but it is not the primary hormone that prepares the endometrium for implantation.

**Clinical Pearl / High-Yield Fact**
In a woman with an infertile workup, the presence of proliferative endometrial changes suggests that the ovary is responding to estrogen, but progesterone support is necessary to prepare the endometrium for implantation.

**Correct Answer:** C. Progesterone