How many counts of vermouth are used in a Gibson martini?

A Gibson martini typically contains a measure of dry vermouth that complements the gin, enhancing the cocktail's flavor profile. The common practice for a Gibson is to use one count of vermouth, which is why the answer is correct. This count allows the vermouth to provide a subtle herbal note without overpowering the gin's characteristic taste.

In the context of cocktail preparation, the 'count' refers to a method of measuring the amount of liquid by counting the pours, which often varies by the bartender's technique but is generally standardized for consistency. For a Gibson, a single count of vermouth strikes a balance, ensuring that the drink remains spirit-forward while still contributing complexity to the flavor.

The other options suggest either too much vermouth, which can turn the drink into a less potent experience, or none at all, which would deviate from the classic recipe that includes this essential ingredient.