Final answer:
The invaginated outer edges of tonsils that help trap materials are called crypts. These structures make it easier for pathogens to move deep into the tonsillar tissues where they can be neutralized by the immune system.
Step-by-step explanation:
The tonsils, which are part of the mucosa-associated lymphoid tissue, play a key role in the body's immune defense. Specifically, tonsils have multiple germinal centers and invaginated outer edges called crypts that help trap material.
These crypts accumulate debris taken into the body through eating and breathing, and they encourage pathogens to penetrate deep into the tonsillar tissues where they are acted upon by numerous lymphoid follicles and thus eliminated.
The removal of tonsils may be considered in children who have recurring throat infections to prevent the swelling of the palatine tonsils from interfering with breathing or swallowing. The correct option is A. crypts