Step 1: Define each term in one line.
Gametogenesis is making sperm and egg. Fertilization is sperm and egg joining into a zygote. Implantation is the embryo attaching to the uterus wall. Gestation is the whole growth period inside the uterus. Parturition is childbirth.
Step 2: Fix what must come first and last.
Gametes have to exist before fertilization can happen, so gametogenesis is always first. Childbirth is by definition the end of pregnancy, so parturition is always last.
Step 3: Order the middle three by logic.
Fertilization has to happen before there is any embryo to implant, so fertilization comes before implantation. Once the embryo implants, it grows through the gestation period until birth, so implantation comes before gestation.
Step 4: Rule out the other listed orders.
Any order that puts implantation or gestation before fertilization is wrong, because there is no embryo to implant or grow before fertilization occurs. This removes the sequences that place gestation or implantation earlier than fertilization.
Final Answer:
The correct sequence is gametogenesis, fertilization, implantation, gestation, parturition, option (4).