**Core Concept**
The signs of early pregnancy are primarily related to the changes in the uterus, ovaries, and endocrine system. These changes occur due to the implantation of the fertilized ovum in the uterus and the subsequent production of human chorionic gonadotropin (hCG) hormone.

**Why the Correct Answer is Right**
The correct answer is related to the fact that early pregnancy is characterized by changes in the uterus, such as the uterus becoming slightly larger and softer than usual. The cervix also becomes more effaced and the uterine cramping can be felt. Another sign of early pregnancy is the presence of a "ring of fire" sensation, which is due to the implantation of the blastocyst. This can cause a slight spotting or bleeding.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is a common sign of early pregnancy. The basal body temperature (BBT) is known to rise after ovulation due to the production of progesterone hormone, which helps in maintaining the early stages of pregnancy.
* **Option B:** This option is incorrect because it is a sign of early pregnancy. The presence of a positive pregnancy test, which detects the presence of hCG hormone in the urine, is a definitive sign of pregnancy.
* **Option C:** This option is incorrect because it is a sign of early pregnancy. The implantation of the blastocyst in the uterine lining can cause a slight spotting or bleeding, which is a common symptom of early pregnancy.

**Clinical Pearl / High-Yield Fact**
It's essential to note that not all women experience the same symptoms of early pregnancy, and some may not experience any symptoms at all. A missed period is often the first sign of pregnancy, and a urine pregnancy test is usually performed to confirm the pregnancy.

**Correct Answer: C.**