Question 4 - Please show the work that gave you the answer so I can understand

When researchers were trying to figure out what caused polio, they saw a connection between ice cream sales and polio. As ice cream sales increased so did the incidences of polio. Does that mean that eating ice cream causes polio? () YES: The two events are directly proportional, "cause" and "effect". O NO: It could totally be coincidental that ice cream sales and number of cases of polio increased at the same time