For the purposes of this act a trustee shall be deemed to be engaged in war service in any of the following instances:

    (a) If he is a member of the military, naval or air forces of the United States of America or any of its allies;

    (b) If he is engaged in any work beyond the borders of the state of Michigan in connection with a governmental agency of the United States of America, or in connection with the American Red Cross or any other body with similar objects;

    (c) If he is interned in any enemy country or is in a foreign country or a possession or dependency of the United States of America and is unable to return to the state of Michigan;

    (d) If it shall appear to the court that he is engaged in any occupation which is in direct aid of the war effort of the United States of America, or any of its allies, and which necessitates his continuous and extended absence from the state of Michigan.