Which of the following statements about fetoplacental circulation is NOT true?

Correct option is D

In the placenta, maternal and fetal blood remain separated by placental barrier; exchange occurs via diffusion and active transport. Blood never mixes directly.
Explanation of options: (a) ✔ True; no direct connection. (b) ✔ True; exchange via diffusion, facilitated transport. (c) ✔ True; maternal spiral arteries empty into intervillous space. (d) ✘ Incorrect; blood does not mix directly.