と

パン ___ 卵を 買いました。

The particles "と" (to) and "や" (ya) both mean "and." "と" is used to list all items exhaustively, meaning only bread and eggs were bought. "や" is used to list a few examples among others, implying that other things might have been bought too.

助詞「と」と「や」は、物事を並列に繋げる「と」と「や」です。「と」は全てを、「や」はいくつか例を挙げるときに使います。例：「本とペン。」