The correct answer is A. Economic connections.
Nowadays, we live in a single global economy. This means that all the actions of all the producers and consumers of goods and services in the world and all the agents of the global financial market are interlinked. In general terms, soy that is produced in Brazil is consumed in China, Saudi Arabian oil fuels American and European cars, and financial market agents tend to check the state of the interest rate of Argentina to see whether they would invert their money there or in some South-East Asian country. One small perturbation in one of this countries or local economies usually affects to some degree the rest of the global economic system.