Vitamin K, also known as phylloquinone, is made by plants, and is found in highest amounts in green leafy vegetables because it is directly involved in photosynthesis. It may be thought of as the plant form of vitamin K. It is active as a vitamin in animals and performs the classic functions of vitamin K, including its activity in the production of blood-clotting proteins. Animals may also convert it to vitamin K.

Answer this question based on the passage: what are the main sources of vitamin k? OK. Let's think. My stream of consciousness:
To answer the above question, the relevant sentence is: Vitamin K, also known as phylloquinone, is made by plants, and is found in highest amounts in green leafy vegetables because it is directly involved in photosynthesis. The answer is green leafy vegetables.