Final answer:
A positive pregnancy test confirms the presence of hCG hormone in the urine, indicating that the woman is pregnant.
Step-by-step explanation:
The positive sign of pregnancy among the given options is a. Positive pregnancy test. A positive pregnancy test confirms the presence of human chorionic gonadotrophin (hCG) hormone in the urine, which is produced by the fetus and later by the placenta. The presence of hCG indicates that fertilization has occurred and the woman is pregnant.