The simple Marshall-Lerner condition would suggest that one of the following cases would produce a worsening of the trade balance if the country’s currency depreciated. Which one? (The negative sign on elasticities is being ignored; also, assume that trade is initially balanced.)
选项：

A: elasticity of demand for exports = 0.8; elasticity of demand for imports = 0.5
B: elasticity of demand for exports = 0.4; elasticity of demand for imports = 0.6
C: demand curve for exports is vertical; demand curve for imports is horizontal
D: elasticity of demand for exports = 0.8; elasticity of demand for imports = 0.1