500
On the day Evie brings her pet fish home from the pet store, he swims to the top of the fishbowl when she puts in food. After several weeks, the fish swims to the top when Evie comes over and opens up the fish food container. Identify the CS, US, CR, and UR
CS: opening the container of food
CR: Swimming to the top when the food is opened
US: Food in the fish bowl
UR: Swimming to the top when food is put into the bowl