Which of the following sentences is punctuated correctly? once in awhile i like to get up early in the morning to see the sun rise, because of the beautiful colors that the sky turns when the sun is coming up. my favorite class in elementary school was art, because i got to create all kinds of pottery. all of the frogs had buried themselves deep in the mud because they wanted to stay warm

Well i would say it would be between the last two, but choosing one maybe it would be the last one. This is because in the second to last one, the comma doesn't sound like it belongs there. See? try saying it. remember the comma means a pause in the sentence. So the only thing missing in the last one is a period but i am assuming that you meant to put one there.

The answer is letter government-planned economy.   Americans have been successful because of their independent spirit.  They do not want government to dictate how they do business.  To that is an infringement on their freedom and their rights.  They believe that it would limit their profits and hinder their freedom if government interferes too much on their business affairs.