What feature is characteristic of a longbow?

A longbow is characterized by its straight limbs. This design is important because it allows for a more efficient transfer of energy during the draw and release of the arrow. The straight limbs contribute to the bow's overall performance, providing a longer power stroke that can generate greater speed and distance when shooting arrows.

The other features mentioned in the alternatives do not align with the traditional attributes of a longbow. Short limbs would typically be associated with a composite or recurve bow, which has a different design and function. A curved design would also not be applicable to a longbow, which is typically known for its simplicity and straight form. Adjustable sights are features commonly found on modern compound bows, but they are not characteristic of traditional longbows, which rely more on the archer's skill and instinct for aiming.