19 (Mandatory) (1 point) A questionnaire for couples asked the participants to provide their age. For each partner there was an open-ended question such as: Please tell us your age in years: _______ The researchers were interested in the average age of the couple. For this they computed the average age by adding the two ages and then dividing the resulting number by two (i.e., the arithmetic mean). For instance, first partner = 20 and second partner = 40; average age = 30. Which measurement level is the average age? Question 19 options: Ordinal level Ratio level Interval level Nominal level One cannot measure age this way