It's obvious that the best fit answer would be "Take your time." I felt the whole dialogue sounds odd, since Ann wonders "how much time," not "should I worry or hurry," thus it sounds as if Ann doesn't know the deadline yet.
I did the test since I was considering sending my niece to learn English there. But the test gave me a second thought. (And not to mention the missing of a period after the word "yet.")
My question here is, would a native find the dialogue unnatural?