Answer:
C: Rational numbers
Explanation:
The change received in a cash purchase, if given in £ (or $) would most certainly be a Rational number (that is a number that can be represented as a/b where a and b are coprimes). However if measured in p (or cents) then the answer would be whole numbers.
You cannot go wrong with option C as whole numbers (integers) are a subset of rational numbers. That is, all whole numbers are rational numbers.