Answer:
D Price of a pencil
Step-by-step explanation:
In A the number of students has to be an integer because you can't have part of a student
In B most likely your teacher will give you your score in a whole number form like 95% and not 94.87% because they would round it if it isn't a whole number already
C is similar to A you can't have a part of a computer key
Lastly in D stores very frequently have there prices at something like $1.99 which isn't a integer
