Which piece of evidence most strongly supports the policy that 'no amount of alcohol is safe during pregnancy'?

• A. A single case report showing no adverse outcomes after heavy drinking in one pregnancy, proving that population-wide recommendations are unnecessary.
• B. Longitudinal research demonstrating that alcohol exposure during the third trimester only causes transient, fully reversible learning delays that resolve by early childhood in all cases.
• C. The inability of the early embryo/fetus to effectively metabolize alcohol combined with data showing a range of dose-independent outcomes (FASD spectrum) and the absence of a known safe threshold for critical developmental periods.
• D. Epidemiologic studies that conclusively demonstrate moderate drinking improves fetal neurodevelopmental outcomes compared with complete abstinence in randomized controlled trials.

Answer: (C)