True statements about vitamin K are: a) Increases the synthesis of factor II, VII, IX and X b) Require exposure to sunlight c) Causes hemolytic anemia in patients with G–6–PD deficiency d) t1/2 is < 6 hour

Vitamin K is a group of structurally similar, fat-soluble vitamins that the human body requires for complete synthesis of certain proteins that are prerequisites for blood coagulation (K from Koagulation, Danish for "coagulation") and which the body also needs for controlling binding of calcium in bones and other tissues. The vitamin K-related modification of the proteins allows them to bind calcium ions, which they cannot do otherwise. Without vitamin K, blood coagulation is seriously impaired, and uncontrolled bleeding occurs. Preliminary clinical research indicates that deficiency of vitamin K may weaken bones, potentially leading to osteoporosis.