**Core Concept**
The corpus luteum is a temporary endocrine structure in the female ovaries that plays a crucial role in the menstrual cycle and early pregnancy. It forms after ovulation and produces progesterone to prepare the uterus for a potential pregnancy.

**Why the Correct Answer is Right**
The corpus luteum functions for approximately 10 days in a nonpregnant female. After ovulation, the ruptured follicle in the ovary undergoes luteinization, resulting in the formation of the corpus luteum. The corpus luteum produces progesterone, which maintains the endometrium in a state of proliferation and prepares it for implantation of a fertilized ovum. If pregnancy does not occur, the corpus luteum degenerates, and progesterone levels drop, leading to menstruation. This process is known as the luteal phase of the menstrual cycle.

**Why Each Wrong Option is Incorrect**
**Option A:** 5 days - This is too short a duration for the corpus luteum to function, as it would not provide sufficient time for implantation of a fertilized ovum.

**Option C:** 14 days - While the corpus luteum can produce progesterone for up to 14 days, this duration is typically seen in pregnant females, where the placenta takes over progesterone production.

**Option D:** 30 days - This is an excessively long duration for the corpus luteum to function in a nonpregnant female.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that the corpus luteum is a critical structure in the menstrual cycle, and its dysfunction can lead to issues such as luteal phase defects, which can cause anovulatory cycles and infertility.

**✓ Correct Answer:** B. 10 days