(PT9 S4- #13)

J: worked 3 years and will vacation 4 weeks this year

Everyone who worked 1-4 years entitled to 3 week vacation

Apply half of unused vacation to next year.

So it makes sense to me that J had two weeks left over from last year so she got half of that this year

(A) J did not use two weeks in which she was entitled to

(C) J only used one week in which she was entitled to

What is the difference between the two and how can I distinguish them?