The correct answer is B. An embryo or fetus dies during the first 20 weeks of pregnancy.
Step-by-step explanation:
A miscarriage occurs when a fetus (unborn human in development) dies and therefore the pregnancy ends. This term is used especially when this occurs during the first 20 weeks or the first five months of a pregnancy and differs from abortion because it has natural causes or it is not induced. Additionally, miscarriages are common during early pregnancy and in some cases might require treatment to avoid infections and other medical complications. According to this, during a miscarriage "an embryo or fetus dies during the first 20 weeks of pregnancy".