Corpus luteum functions maximally without an implantaton for …… days :

**Core Concept**
The corpus luteum is a temporary endocrine structure in the female ovaries that plays a critical role in the menstrual cycle and early pregnancy by producing **progesterone**. Its function is essential for preparing the uterus for a potential pregnancy. The lifespan and function of the corpus luteum are closely regulated by hormonal feedback mechanisms.

**Why the Correct Answer is Right**
The corpus luteum produces progesterone to thicken the uterine lining, making it suitable for implantation of a fertilized egg. Without implantation, the corpus luteum functions maximally for about 10 to 14 days after ovulation, after which it degenerates if no human chorionic gonadotropin (hCG) is present to maintain its function. This timeframe allows for the potential implantation of a fertilized egg and the initiation of pregnancy.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the corpus luteum's maximal function without implantation does not last this short duration.
**Option B:** This option might seem plausible but is not accurate regarding the duration of maximal corpus luteum function without implantation.
**Option D:** This option is incorrect as it suggests a duration longer than the actual lifespan of maximal corpus luteum function without implantation.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the corpus luteum's function is prolonged by the presence of hCG in pregnancy, which prevents its degeneration and ensures continuous progesterone production until the placenta takes over this role.

**Correct Answer:** C. 10 days