Why do the Tropical North's nations have a history of tense relations and internal unrest?

Marine exptoration of oil uses seismic waves to locate oil in the seabed. what is a negative impact from seismic waves on the aquatic ecosystem of the ocean? a. seismic waves kill microoganisms b. seismic waves disrupts the sand and causes seafloor erosion c. seismic waves have virtually no adverse affects on marine life d. seismic waves damage the sonar that dolphins and whales use to orient themselves underwater

In their competition for power nations raced to

Before world war 1 started, austria-hungry was wary of (spain or serbia) because of border disputes