**Core Concept**
Oestrogen is a steroid hormone that plays a crucial role in the development and maintenance of female reproductive organs and secondary sexual characteristics. It also has various effects on the cardiovascular system, bone health, and the brain.

**Why the Correct Answer is Right**
Oestrogen promotes the growth and thickening of the endometrium, preparing it for potential pregnancy. It also stimulates the growth of breast tissue and maintains bone density, particularly in postmenopausal women. Additionally, oestrogen has a protective effect on the cardiovascular system by increasing HDL (good) cholesterol and reducing LDL (bad) cholesterol levels.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided. Please provide the complete question.

**Option B:** This option is not provided. Please provide the complete question.

**Option C:** This option is not provided. Please provide the complete question.

**Clinical Pearl / High-Yield Fact**
One of the key differences between oestrogen and progesterone is their effects on the endometrium. Oestrogen causes the endometrium to proliferate, while progesterone causes it to differentiate and prepare for implantation.

**Correct Answer:** Not enough information provided to give a correct answer. Please provide the complete question with all options.