Bus rides and canned soup are inferior goods, so the ________ elasticity of demand is ________. (公交车和罐装汤是劣质商品,所以 _ _ _ _ _ _ _ _需求弹性是 _ _ _ _ _ _ _ _。——中文由在线翻译而来,仅供参考)
选项：

A:cross; positive交叉;正
B:income; positive收入;正
C:income; negative收入;负
D:cross; negative交叉;负