World trade has grown substantially in the last 60 years. For example, while world output grew at an annual rate of 3.8% per year between 1950 and 2003, world exports grew at 10.8% per year over the same time period. Which of the following help to explain the increase in international trade and finance since the 1950s? Check all that apply. a. Better high-speed rail linesb. Increases in the global populationc. Services such as web conferencing and teleconferencing that facilitate international meetingsd. International trade agreements such as the North American Free Trade Agreement (NAFTA)