Select the incorrect statement. Question 34Select one: a. For most groups of countries, total public debt as a percentage of real GDP has been increasing since the 1970s. b. When economists speak in terms of public debt, it is common for them to refer to or use the term, 'debt-to-GDP'. c. When there is an economic crisis that affects debt levels, then the debt-to-GDP ratio will increase even if no new debt is incurred. d. For most groups of countries, total public debt as a percentage of real GDP has been decreasing since the 2010s