A research team is investigating whether adding salt to chocolate milk improves the taste. Over several days and times of day, a researcher fills red and blue cups with the same brand of chocolate milk, then adds a pinch of salt to each of the blue cups. A second researcher, who does not know which cups have the added salt, takes the cups to a nearby grocery store. Willing customers are given one blue cup and one red cup to drink, and each customer rates the taste of the milk in each cup on a scale from one to ten. The customers are unaware which cup has the added salt. The second researcher keeps a record of the cup color and the associated taste score. At the end of the study, the first researcher will compare the taste scores between the two salt statuses (salted and unsalted). (a)First choose whether the procedure described above is an observational study or a designed experiment. Then further categorize the procedure by choosing the correct type of observational study or designed experiment. Observational study Designed experiment prospective double-blind retrospective completely randomized