The correct options are
B Unwillingness to abide by international treaties
C Arm race between the countries
D Influx of refugees from other countries
International borders are always prone to attacks and conflicts. In the absence of surveillance by either country, the chances of disputes between the two nations increase. Unwillingness to abide by international treaties, constant competition, arm race, and the influx of refugees from other nations are some of the possible reasons. Cooperation in the field of education promotes friendliness amoung the countries.