Final answer:
The environmental factor affected by increased global terrorism leading to border congestion and higher costs is classified as a security factor, which impacts human migration and international trade. The correct answer is option: D. Security.
Step-by-step explanation:
The increased costs and time associated with the movement of personnel, materials, and equipment across international borders due to global terrorism can be classified as a security environmental factor. This is because it directly relates to measures taken to protect the borders and ensure safety from threats such as terrorism. As border security tightens, it often leads to border congestion, which subsequently increases the costs and time required for such movements.
Understanding the effect of security issues on human migration and international trade requires a multifaceted approach, considering how political, economic, social, and environmental push and pull factors, as well as physical geography, influence these dynamics.