In a specimen-based viva, the examiner describes this case: small external openings along the sides of an insect body lead into air tubes. Choose the concept that fits it best.

Correct Answer: D

spiracles

Spiracles are openings of the insect tracheal system. They allow air to enter and leave the tracheae and can help regulate water loss. This MCQ belongs to the Insecta topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.