Final answer:
Recruits in a typical regiment were often united by their local or regional origin, which was especially true in certain conflict periods like World War I where "pals" units were common.D is the correct answer.
Step-by-step explanation:
The characteristic that recruits in a typical regiment shared was typically geographical origin.
While many variables such as age, economic status, or immigration status did affect composition, the most common unifying element among recruits was their local connection. For example, during World War I, the British army's "pals" units consisted of young men from the same community who signed up together and were assigned to the same unit. This practice, however, was discontinued after the Somme campaign in 1916 due to high casualties affecting whole communities. Moreover, in the Roman period, soldiers from the provinces were integrated into Roman culture through military service, regardless of their origin within the empire.
In the context of the options presented, the mentioned correct option in the final answer would be (d) They were all from the same town, although it should be noted that the exact nature of regiments can vary depending on the time period and military organization in question.