Respuesta :
It says everything in three paragraphs it’s from a period tracker called Clue

Hi !
Answer:
When one sperm penetrates the wall of the ovum.
Fertilization occurs when one sperm penetrates one ovum, producing a viable zygote. Fertilization occurs in the fallopian tube, not when the ovum is expelled from the ovary or in the uterus. After the sperm penetrates the ovum in a fallopian tube, the impregnated ovum travels down the tube to the uterus.