Which of the following is a component of second-degree assault?

In the context of second-degree assault, causing physical injury with intent using a dangerous instrument aligns perfectly with the legal definitions typically outlined for this crime. Second-degree assault generally involves intentionally causing physical harm to another person, and the use of a dangerous instrument elevates the severity of the act. This means that not only is there an intention to cause harm, but the method used — a dangerous instrument — indicates a higher degree of culpability and potential for serious injury.

The other options do not fit the standard components of second-degree assault. Causing serious injury with criminal negligence refers to a different legal framework, often related to involuntary actions rather than intent. Threatening no physical harm does not constitute assault, as there is no actual physical injury or intent to inflict that injury. Lastly, causing harm to a third party could imply different charges depending on the circumstances, but it again does not define second-degree assault against a direct victim as required by the definition of the crime. Therefore, choice B accurately captures the essence of second-degree assault by emphasizing both intent and the use of a dangerous instrument.