The three first-line examinations of improving the early diagnosis of gastric cancer are：
A
esophagogastroscopy，cytology of gastric juice，and barium meal X-ray
B
esophagogastroscopy，acid measure of gastric juice，and barium meal X-ray
C
esophagogastroscopy，occult blood test of feces，and barium meal X-ray
D
cytology of gastric juice，occult blood test of feces，and esophagogastroscopy
E
cytology of gastric juice，tetracycline fluorescence test，and barium meal X-ray