What is the common ratio for a classic whiskey sour?

The classic whiskey sour is typically made using a ratio of 2 parts whiskey to 1 part lemon juice and 1 part simple syrup. This balance creates a well-rounded cocktail where the warmth and depth of the whiskey are complemented by the tartness of the lemon juice and the sweetness of the simple syrup.

Using this 2:1:1 ratio allows the whiskey to be the prominent flavor, while ensuring that the sour and sweet elements enhance rather than overpower the spirit. The lemon juice adds necessary acidity, which is essential in balancing the drink, and the simple syrup provides enough sweetness to create harmony among the flavors. This combination is what establishes the whiskey sour as a classic cocktail, making option A the correct answer.