In a physiological experiment, a medical student noticed a large amount of pancreatic secretion when the acidic chyme entered the small intestine. Which of the following mechanism could explain this phenomenon? ()
A．Vagus
nerve excitement
B．Small
intestine mucosa releases gastrin
C．Sympathetic
excitement
D．Intestinal
mucosa releases secretin
E．Acidic
chyme directly stimulate pancreatic secretion