18) D

On Monday, Jasper has maths and English before breaktime. This means he carries 4 books before breaktime. After breaktime he has history which requires 2 books. 4 + 2 = 6 Remember that he can only carry 5 books at one time. So he would need to visit the locker at break time on Mondays.

On Tuesday, Jasper has music and science before breaktime. This means he carries 3 books before breaktime. After breaktime he has geography which requires 3 books. 3 + 3 = 6 So he would need to visit the locker at break time on Tuesdays.

On Wednesday, Jasper has maths and history before breaktime. This means he carries 5 books before breaktime. After breaktime he has science which requires 2 books. 5 + 2 = 7 So he would need to visit the locker at break time on Wednesdays.

On Thursday, Jasper has music and English before breaktime. This means he carries 2 books before breaktime. After breaktime he has maths which requires 3 books. 2 + 3 = 5
So he would not need to visit the locker at break time on Thursdays.