When it becomes necessary for purposes of this subchapter to determine whether a person who participated in sexual conduct was a child under eighteen (18) years of age, the court or jury may make this determination by any of the following methods:
(1) Personal inspection of the person;
(2) Inspection of the photograph, motion picture, or other material that shows the person engaging in the sexual performance;
(3) Oral testimony by a witness to the sexual performance as to the age of the person based on the person's appearance at the time;
(4) Expert medical testimony based on the appearance of the person engaged in the sexual performance; or
(5) Any other method authorized by law.