Which of the Following Is the Most Likely Explanation for the Absence

question 1

Multiple Choice

Which of the following is the most likely explanation for the absence of a protective filter blocking the passage of alcohol between the maternal and fetal circulations in humans?

• A) There has not been enough time to evolve such a barrier.
• B) Such a barrier would probably also block important molecules that need to be passed to the fetus.
• C) The maternal and fetal blood mix directly together in an area with many villi, so a barrier is impossible.
• D) Alcohol has some positive effects on the fetus, so evolution has resulted in an intermediate level of filtering that blocks all but the worst abuses of alcohol.