At which thoracic vertebra does the trachea divide into right and left primary bronchi?

Given below are two statements regarding the respiratory system of man.
$Statement-I$: Epiglottis prevents the entry of food into the trachea.
$Statement-II$: The internal lining of the trachea is made up of ciliated epithelium only.
In the light of the above statements, choose the most appropriate answer from the options given below:

Which structure in humans is analogous to the spiracles of a cockroach?

The largest cartilage of the larynx is an example of which type of cartilage?

During the act of swallowing,which of the following structures prevents the food bolus from entering the glottis?

Analogy type questions:
$(1)$ Sponges,Coelenterates : Respiration through entire body surface :: Insects : ....
$(2)$ Larynx : Cartilaginous box :: Epiglottis : .......