What is the signet ring-shaped cartilage?

Which part of the thyroid cartilage is closed?

Primary,secondary,tertiary bronchi and initial bronchioles are supported by:

In man and mammals, air passes from outside into the lungs through which of the following sequences?

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

Identify which respiratory structure possesses the following features and choose the correct option accordingly.
$I.$ Found in mammals
$II.$ Highly muscular and fibrous partition,elevated towards the thorax like a dome
$III.$ Separates thoracic and abdominal cavity