Changes in GnRH pulse frequency in females is controlled by circulating levels of:

Options

A. osestrogen and ihibin
B. progesterone only
C. progesterone and inhibin
D. oestrogen and progesterone

Explanation

To solve the question regarding the changes in GnRH pulse frequency in females and what controls it, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Role of GnRH**:
- Gonadotropin-Releasing Hormone (GnRH) is produced by the hypothalamus and is crucial for the regulation of the reproductive hormones.

2. **Identify the Hormones Involved**:
- The question provides several options: estrogen, inhibin, progesterone, and combinations of these hormones.

3. **Recognize Feedback Mechanisms**:
- Hormones like estrogen and progesterone can exert negative feedback on the hypothalamus. This means that when their levels are high, they signal the hypothalamus to reduce the release of GnRH.

4. **Analyze the Options**:
- The options given include:
- Estrogen and inhibin
- Progesterone and inhibin
- Estrogen and progesterone
- Estrogen and progesterone (combined)
- Among these, the combination of estrogen and progesterone is known to have a significant impact on the feedback mechanism.

5. **Conclude the Correct Answer**:
- Based on the understanding of hormonal interactions and feedback mechanisms, the correct answer is the combination of **estrogen and progesterone**, as they are responsible for controlling the changes in GnRH pulse frequency in females.

### Final Answer:
The changes in GnRH pulse frequency in females is controlled by circulating levels of **estrogen and progesterone**.

---