Answer:
The level of variable ages of children is ratio.
Explanation:
Nominal scale is the one which takes categories as its values like gender of a person.
Ordinal scale is the one which is used to show the order of values with no clear difference among them like satisfaction level of people with a service.
Interval scale is the one which shows the clear order of values with clear difference between the values with out true zero.
Ordered scale is one which not only produces the order of variables but also makes the difference between variables known along with information on the value of true zero.
Therefore, the variable which is under consideration here is the ages of children, which takes the values 3,4,5,6 and 7 is a ratio scale.