The primary purpose of most constitutions is to define and limit government power
Answer: Option D
Step-by-step explanation:
Sometimes a constitution does dictate areas where the Government can exercise absolute power(Option E). Power can be synonymous with prevention of a strong central Government (Option C) but it is not necessarily be defined.
A constitution is not a substitute for Government but rather it talks about how the Government must function and not necessarily constitution must define a moral code for people to follow (Option A). Although it does it some instances, it does not always.
In short, the aim and working of the constitutions are to inform the federal governments what they can and cannot act on behalf of states. And also, make sure that "people" are responsible to the government, not any other ways around.