The main mechanism by which acid chyme enters the small intestine and causes the secretion of large amounts of pancreatic juice is

A、releaseofgastrinbythemucosaofthesmallintestine;
B、releaseoftrypsinbythemucosaofthesmallintestine;
C、thesmallintestinalmucosareleasescholecystokinin;
D、excitationofvagusnerve