（ ） 如擔保信用狀內容載明WE HAVE BEEN INFORMED THAT ABC CO. HAS ENTERED INTO CONTRACT NO. 1234 DATED MAY 5, 2006 WITH YOU, FOR THE SUPPLY OF FOUR SETS OF MACHINE，依文觀意，請問這是何種型態之擔保信用狀？
(A) 投標保證
(B) 預付款保證
(C) 借款保證
(D) 履約保證