To solve this problem, we need to understand the process of polar body extrusion during oocyte development and fertilization.$\newline \bullet$During oogenesis, the primary oocyte undergoes the first meiotic division to form a secondary oocyte and the first polar body.$\newline \bullet$The secondary oocyte is arrested in metaphase II until fertilization occurs.$\newline \bullet$Upon entry of the sperm into the secondary oocyte, the second meiotic division is completed, leading to the extrusion of the second polar body.$\newline \bullet$This occurs after the sperm enters the egg but before the actual fusion of the sperm and egg nuclei, which is fertilization.$\newline$Therefore, the extrusion of the second polar body occurs after the entry of sperm but before fertilization.$\newline$This corresponds to Option 1.