Which statement best describes why fetal cfDNA in maternal blood is considered placental in origin?

Which statement best describes why fetal cfDNA in maternal blood is considered placental in origin?

• A. Because fetal DNA is derived from paternal cells circulating in maternal blood.
• B. Because the fetal DNA fragments reflect placental trophoblasts rather than direct fetal tissues.
• C. Because the placenta secretes all maternal DNA.
• D. Because only maternal DNA can cross into maternal blood.

Answer: (B)