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.
I would tell him that other foods give you vitamin A other than carrots and he probably gets the recommended amount of vitamin A without knowing it, or he could just eat another carrot if he's that worried about it.
