Which of the following is a sign of a potentially sophisticated terrorist group?

A sign of a potentially sophisticated terrorist group is advanced methods of attack. This indicates a high level of planning, resources, and expertise within the group. Sophisticated tactics may include the use of technology, sophisticated weaponry, and coordinated operations that require extensive training and logistics. Such capabilities suggest that the group has invested significant time and effort into its operational capabilities, indicating a serious threat.

In contrast, options like frequent media appearances could simply signify an effort to gain public attention, but do not necessarily reflect the sophistication of the group's operational methods. Lack of organized leadership and absence of strategic planning suggest a disorganized or ineffective group, which would be less likely to employ advanced methods of attack. Thus, advanced methods of attack serve as a clear indicator of a well-organized and capable terrorist group.