Consider the following knowledge base

represented as a set of Prolog facts:

age(harry,13).
age(draco,14).
age(ron,13).
age(hermione,13).
age(dumbledore,60).
age(hagrid,30).

Which of the following queries return in a single answer

all

the age numbers recorded in the knowledge base? (A solution which returns duplicates is equally acceptable with one that does not).