Answer:
The Third Variable Problem is exemplified in this scenario.
Explanation:
Variables are what are studied during research and there can be various types such as independent or dependent, amongst the most common.
The third variable problem refers to a confusion in which a third variable in a study creates a mistaken thought about the relation of 2 variables.
In this case, Gary's variables are the beer sales and number of road accidents. He makes a relation between the two but then a third variable, the time of year, causes a mistaken conclusion regarding the two other variables, thus affecting the results.