问题

They were ________ busy ________ with each other________ the time.
A: too; talking; toforget
B:so; talking; that they forgot
C:so; to talk; that they forgot
D:too; to talk; to forget
B:so; talking; that they forgot
C:so; to talk; that they forgot
D:too; to talk; to forget
正确答案是: