Basic regression assumes that effects are linear and don't depend on other variables. Which of the following would violate that assumption? Group of answer choices A case where you think increasing tariff rates has a substantial effect on trade when tariffs are low, but not when tariffs are high A case where you think democracy reduces tariff rates which then increase trade A case where you think small countries might both have lower tariff rates and for separate reasons trade more A case where you think increasing tariff rates has a substantial effect on trade in wealthy countries, but little effect in poor countries