Which of the following is the largest hawk?

The largest hawk among the choices listed is the Jerkin. Jerkin is a term often used in falconry to refer to a female hawk, particularly the larger species. Female birds of prey are typically larger than their male counterparts, which is known as sexual dimorphism. This size difference allows them to tackle larger prey. The Jerkin, being associated with larger hawks, exemplifies this trait.

The other options do not refer to hawk species in the same way. Jack typically refers to a male hawk, and tiercel is specifically a term used in falconry to denote a male falcon. Moreover, while falcons are also raptors, they are a different genus and are generally not classified under the same size category as larger hawks. Therefore, the Jerkin stands out as the largest option among the given choices.