## Core Concept
Granulosa cells are a type of cell in the ovaries that play a crucial role in the development and maturation of follicles. They are involved in the production of estrogen and progesterone, which are essential for the menstrual cycle and fertility. The main functions of granulosa cells include the production of sex hormones and the support of oocyte growth.

## Why the Correct Answer is Right
The correct answer is related to the functions and characteristics specific to granulosa cells. These cells are known for producing **estrogen** (through the aromatization of androgens to estrogens) and **progesterone**, which are vital for follicular development and preparation for potential pregnancy. They also produce **inhibin**, which inhibits the production of follicle-stimulating hormone (FSH) by the pituitary gland, thus regulating follicular growth.

## Why Each Wrong Option is Incorrect
- **Option A:** This option would be incorrect if it describes a function or characteristic not specific to granulosa cells or not related to them at all. Without specific details on the options, we can infer that any option not directly related to granulosa cell functions would be incorrect.
- **Option B:** Similarly, this would be incorrect if it does not align with known granulosa cell functions or products.
- **Option C:** This option is also incorrect for the same reasons as A and B, assuming it does not accurately describe a role or product of granulosa cells.

## Clinical Pearl / High-Yield Fact
A key point to remember is that **granulosa cells produce inhibin**, which is a hormone that decreases FSH production. This is a critical regulatory mechanism in the menstrual cycle and follicular development. Additionally, the **zona pellucida** around the oocyte is produced by both the oocyte and granulosa cells, highlighting their role in oocyte support.

## Correct Answer: D.