Which word in the sentence has the same meaning as the word obstinate?

Activity 1.3.2 standard and metric measuring pltw

States might choose to cooperate at the regional or global level for all of the following reasons except (2 points) a.) to gain regional political influence b.) to engage in dispute resolution c.) to assure basic human rights d.) to encourage economic interaction e.) to increase national sovereignty

Why does the blending of many different diciplines present both challenges and opportunities to enviromental scientist?