blessings 发表于 2011-10-2 02:19 
(B) 吧。 when there are externalities, the marginal cost is bigger than the marginal benefit. Then t ...
如果不是B的话,那就是A啦。不过what's the rationale there? Can you tell me?
If the marginal benefit is bigger than the marginal cost, that indicates underallocation of resources? Because this kind of resources should be allocated more than before since its MB is bigger than MC?