Which pricing system could be modeled by a discrete function?

Select one:

a.
An ice cream shop sells ice cream for $1.20 per ounce and toppings for $0.55 per ounce.


b.
An ice cream shop sells ice cream and toppings for $5.00 per cup.


c.
None of these


d.
An ice cream shop sells any amount of ice cream for $0.95 per ounce.