prep2-74 in that

74.        (28487-!-item-!-188;#058&003987)

Thirteen states from all regions of the country announced a plan to impose new controls on pollution from truck and bus engines in that they will jointly adopt emission limits that would be far stricter than the federal rules.

(A) to impose new controls on pollution from truck and bus engines in that they will jointly adopt

(B) to impose new controls on truck and bus engines' pollution by the joint adoption of

(C) to impose new controls on pollution from truck and bus engines by jointly adopting

(D) for imposing new controls on pollution from truck and bus engines, and jointly adopting

(E) for imposing new controls on truck and bus engine pollution in the joint adoption of

key：C

关于A中in that 表示becasue的含义，意思上好像也通阿，they指代 Thirteen states ，这样理解有问题吗？

they指代正确。

前后没有因果联系的，by jointly adopting后面的部分只是表示方式，而不是原因。

读逻辑意思很容易发现，是通过...来增加新的控制。