Citizens <em>directly</em>participating in their government is a C. direct democracy
For the United States, it is not.
Article five of the United States Constitution.
"<span>The Congress, whenever </span>two thirds<span> of both Houses shall deem it necessary, shall propose </span>Amendments<span> to this Constitution, or, on the Application of the Legislatures of </span>two thirds<span> of the several States, shall call a Convention for proposing Amendments, which, in either Case, shall be valid to all Intents and Purposes, as Part of this Constitution, when ratified by the Legislatures of</span>three fourths<span> of the several States, or by Conventions in </span>three fourths<span> thereof, as the </span>one<span> or the other Mode of Ratification may be proposed by the Congress; Provided that no Amendment which may be made prior to the Year </span>One thousand eight hundred and eight<span> shall in any Manner affect the </span>first<span> and </span>fourth<span> Clauses in the </span>Ninth<span> Section of the </span>first<span> Article; and that no State, without its Consent, shall be deprived of its equal </span>Suffrage<span> in the Senate."
This process has happened 26 times and once unconstitutionally (the 16th amendment) for a total of 27 amendments.
To pass a law, there must be a 51% vote in both houses of Congress, and an approval by the president. Or Congress may override the veto by a two-thirds vote. This has been done well over 40,000 times in 2011 alone.
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Harun al-Rashid (786 to 809) who encouraged arts and learning.
Hold on give me a minute then I can help
The most important reason for the collapse of Rome was the failure to actually integrate what they conquered. When Roman soldiers conquered new lands, it was rare that they ever attempted to force their culture, ideals, or laws upon the natives and barbarians. Thus, when the Empire began suffering internal struggles, the natives they had conquered decided to take action, which lead to the swift collapse by barbarian invasion from all sides. It's hard to pick a LEAST important reason, seeing that there were many of them, but I suppose a contender would most likely be the common refusal of the Empire to even acknowledge that barbarians were rising. On the outer edges of their territory, in places like Gaul and Morocco, the Roman government was reluctant to even recognize the threat of the barbarians, thinking that even accepting that these barbarians were causing trouble would weaken their prestige in the public eye.