Which of the Following Factors Increases Insulin but Not Glucagon

Which of the following factors increases insulin but not glucagon secretion?

A) increased blood glucose levels
B) increased amino acids (especially during a protein-rich meal)
C) an anticipatory response mediated through an increase in vagal activity and gastrointestinal hormones
D) increased blood glucose levels and an anticipatory response mediated through an increase in vagal activity and gastrointestinal hormones
E) increased amino acids (especially during a protein-rich meal) , and an anticipatory response mediated through an increase in vagal activity and gastrointestinal hormones