Describe the positioning of the trachea and esophagus in the thorax of the horse.
a) Trachea dorsally, esophagus dorsally in the thorax
b) Trachea ventrally, esophagus dorsally in the thorax
c) Trachea dorsally, esophagus ventrally in the thorax
d) Trachea ventrally, esophagus ventrally in the thorax