The advent of decentralized wastewater treatment systems (DEWATs) has reduced the marginal cost of abatement of pollution from such facilities. The level of optimal pollution abatement will

A) increase.
B) decrease.
C) remain unaffected.
D) first reduce and then increase.
E) first increase and then reduce.

In the years after world war ii, which of the following caused many people from asian and african countries to migrate to europe? a. the end of the soviet union b. new economic opportunities after colonialism ended c. the religious freedom found in europe d. new laws allowing greater numbers of immigrants into european countries