The size of an alcoholic drink equivalent is dependent upon ____.

The size of an alcoholic drink equivalent is dependent upon the beverage's ABV. This is because the ABV (alcohol by volume) directly affects the amount of alcohol present in a drink. The higher the ABV, the more alcohol in the drink, meaning a smaller amount is needed to be considered equivalent to other drinks. In contrast, the type of glass used or the time of day do not affect the amount of alcohol in a drink, only the perception or presentation of it. Similarly, a person's age does not determine the size of a drink, as it is individual preference and tolerance that may influence the size of a drink. Therefore, the correct answer is A, as the ABV is the only factor that directly affects the size of an alcoholic drink equivalent.