________twins- zygote splits 10-14 days postfertilization

• A. Dichorionic/ Diamniotic
• B. Monochorionic/ Diamniotic
• C. Monochorionic/ Monoamniotic
• D. Dizygotic

Answer: (C)

The idea being tested is how the timing of zygote splitting determines how many placental and amniotic membranes the twins share. When the split occurs around 10–14 days after fertilization, both the chorion and the amnion have already formed, so the twins share one chorion and one amniotic sac. This produces monochorionic monoamniotic twins, who are at higher risk for complications like cord entanglement and require close fetal monitoring. Earlier splits produce two placentas and two amniotic sacs (dichorionic diamniotic) or one placenta but two sacs (monochorionic diamniotic) depending on the exact timing, while splits after about day 13–14 can lead to conjoined twins.