The answer is Vein.
Ink is used in a pen to write. Blood is used in a vein to transport oxygen and nutrients throughout the
body.A donation is a gift of money or property to a charity or other organization. An accident is an unexpected and unplanned event that causes damage or injury. A doctor is a person who is qualified to diagnose and treat medical conditions.
Of the four
options, only vein is used in the same way as ink is used in a pen.