Which organ has several functions, including defense, hematopoiesis, red blood cell and platelet destruction, and blood reservoir?

A. sensory perception: Sensation is carried by the dorsal (posterior) root. If only the ventral root is damaged, sensation remains intact.

B. willed movement only: While willed movement is lost because motor commands can't reach the muscle, this is not the only thing lost.

C. reflex activity: The ventral root is the "exit" for all motor commands. Without it, both voluntary movement and involuntary motor reflexes (like the knee-jerk) are impossible in that specific area.

D. both reflex activity and sensation: Sensation is unaffected by ventral root damage.

A. Oropharynx: The oropharynx is the middle part of the throat behind the mouth. It is the primary pathway food must travel through to reach the esophagus; therefore, it cannot be blocked during swallowing.

B. Nasopharynx: This must be blocked by the soft palate and uvula to prevent food and liquids from entering the nasal cavity.

C. Larynx: The larynx must be blocked by the epiglottis to prevent food from entering the "windpipe" and causing choking.

D. Mouth: The tongue blocks the front of the mouth during the "oral stage" of swallowing to ensure food moves backward into the throat rather than forward out of the lips.