The nurse is caring for a client who asks why their newborn needs a Vitamin K injection. What is the nurse's best response?

Most mothers have a diet deficient in vitamin K, which results in the infant being deficient.

Vitamin K prevents the synthesis of prothrombin in the liver and must be given by injection.

Newborns cannot synthesize their own vitamin K which increases their risk of bleeding.

The supply of vitamin K is inadequate for at least the first year and must be supplemented.