Which of the following correctly distinguishes K1 (phylloquinone) and K2 (menaquinone)?

• A. K1 is abundant in green leafy vegetables and is the major dietary source; K2 is produced by gut bacteria and is found in some animal and fermented foods.
• B. Both K1 and K2 are water-soluble vitamins, rapidly excreted in urine, and do not participate in carboxylation of bone proteins.
• C. K2 is the major plant-derived form found in leafy greens and provides anticoagulant effects, whereas K1 is synthesized exclusively by gut microbes and stored in adipose tissue.
• D. K1 exclusively activates osteocalcin while K2 functions only in hepatic clotting factor production; they have completely separate tissue specificities.

Answer: (A)