Beginner Level 初级 (chūjí)
The correct answer to this test is C.
Nǐ huíqu ba, búyòng zài sòng le.
A: 你 回去 吧， 不用 再 送 了。
You can head back, no need to see me off.
Hǎo de, nǐ mànzǒu
B: 好 的，你 慢走。
All right, take care.
A: “快走 (kuài zǒu)” means “to walk fast.”
B: “跑 (pǎo)” means ” to run.”
C: “慢走 (màn zǒu)” literally means “to walk slowly.” Here it means “take care.”
D: “走(zǒu)” means “to walk.”
Chinese Cultural context: In China, the host says “慢走” out of courtesy to get their guests to stay longer.