What has been a major challenge for international civil aviation to achieve global agreement?

The correct answer highlights the significant impact that hijacking and terrorism have had on international civil aviation. Throughout history, incidents of hijacking and terrorist attacks have led to a heightened focus on security measures within the aviation industry. These events created urgent demands for increased safety protocols and international cooperation among governments and aviation authorities. The threat posed by terrorism has compelled nations to navigate complex political landscapes, making it challenging to establish uniform security regulations that are acceptable to all countries.

The push for global agreement has been consistently complicated by differing national policies, priorities, and security strategies shaped by each country's unique experiences with terrorism. Additionally, as new threats emerge, ongoing adjustments to security measures are required, which can further inhibit consensus. This creates an environment where achieving a cohesive and globally accepted framework for aviation security becomes particularly difficult.

Other options present important issues but do not encapsulate the overarching challenge of forming a global consensus in the same way. High operational costs, while significant, are often addressed through economic agreements and partnerships. Technological advancements generally foster innovation and collaboration rather than create barriers. Regulatory variances exist and are a challenge, yet they are primarily a reflection of domestic laws rather than a singular defining problem like the risks associated with hijacking and terrorism.