In recent decades, which of the following terrorist "waves" have occurred, roughly?

The correct response indicates that all three waves of terrorism mentioned are significant and occurred over different time periods.

The left-wing wave, which emerged in the 1960s and lasted into the early 1980s, was characterized by revolutionary movements and ideologies that sought to oppose governmental structures perceived as oppressive. Groups during this period often aimed at promoting socialist or communist ideals and were active in various regions of the world, particularly in Europe and Latin America.

Following that, the ethnonationalist wave extended until the late 1990s, where various ethnic groups sought autonomy or independence from larger political entities. This period saw a rise in terrorism related to national identity, with groups engaging in violence to achieve their aims, often rooted in long-standing grievances and historical conflicts.

The religious wave that began at the end of the 20th century represents a shift in terrorist motivations, where faith-based ideologies became prominent drivers of violence. This wave is particularly noted for the rise of Islamist extremism, where groups, often motivated by a desire to impose their interpretation of religious law, executed large-scale attacks.

Recognizing that these distinct waves have shaped the landscape of terrorism over the decades helps in understanding the evolution of terrorist ideologies and the context in which they