Which of the following statements regarding the muscularis externa of the esophagus is true?
A) The upper third portion of the esophagus consists of smooth muscle, the middle third portion is a mixture of smooth and skeletal muscles, and the lower third consists of skeletal muscle.
B) The entire muscularis of the esophagus consists of skeletal muscle only.
C) The entire muscularis of the esophagus consists of smooth muscle only.
D) The upper third portion of the esophagus consists of smooth muscle, and the remaining portion is a mixture of skeletal and smooth muscles.
E) The upper third portion of the esophagus consists of skeletal muscle, the middle third portion is a mixture of skeletal and smooth muscles, and the lower third consists of smooth muscle.
E) The upper third portion of the esophagus consists of skeletal muscle, the middle third portion is a mixture of skeletal and smooth muscles, and the lower third consists of smooth muscle.
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Answer the following statement true (T) or false (F)