Explanation:
Explanation:

The external ear of mammals consists of two main parts:

1. Pinna: The pinna is the visible, external part of the ear that serves to collect sound waves from the environment and funnel them into the ear canal.

2. Auditory meatus: The auditory meatus (or ear canal) is the tube that carries sound waves from the pinna to the tympanum (eardrum).

The combination of the pinna and auditory meatus forms the external ear structure responsible for collecting and channeling sound.


Let’s examine the other options:

#A. pinna and tympanum
- The tympanum (eardrum) is a part of the middle ear, not the external ear. The external ear includes the pinna and auditory meatus, but not the tympanum.

#B. pinna only
- The pinna alone is part of the external ear, but it is not the entire external ear. The auditory meatus is also essential for sound transmission.

#C. auditory meatus only
- The auditory meatus is important, but it works in conjunction with the pinna to form the full external ear.

#E. auditory meatus and tympanum
- The tympanum is part of the middle ear, so this combination is incorrect. The external ear only consists of the pinna and auditory meatus.


Summary:
The external ear of mammals includes both the pinna and the auditory meatus.