I'm a non-native speaker. I'm having a problem with "take care" and "be careful". This problem comes from a text:
Jack: "I've got to go, Sarah. So long."
Sarah: "So long. Jack. And..."
A. be careful
B. don't hurry
C. take care
D. don't take it seriously.
I choose "be careful" but my teacher choose "take care" as the answer. Can someone explain this to me, please?