The Mississippi River which is over 2300 miles long is the second-longest river in the United States.
1. The Mississippi River which is over 2300 miles long is the second-longest river in the United States. (No commas)
2. The Mississippi River, which is over 2300 miles long is the second-longest river in the United States.
3. The Mississippi River which is over 2300 miles long, is the second-longest river in the United States.
4. The Mississippi River, which is over 2300 miles long, is the second-longest river in the United States.

4). The Mississippi River, which is over 2300 miles long, is the second-longest river in the United States.

Explanation:

As per the question, option 4 i.e. 'The Mississippi River, which is over 2300 miles long, is the second-longest river in the United States' most appropriately revises the given sentence to rectify the punctuation error. It correctly employs comma(,) before and the after 'participial phrase' ('which is over 2300 miles long') that involves non-essential description and removing this would not affect the basic meaning of the sentence. Therefore, the comma separates or offsets this non-essential description from the sentence. Thus, option 4 is the correct answer.

the speech this question is referring to is president kennedy's special message to the congress on urgent national needs, may 25, 1961

kennedy responds in a very direct and concrete way to those thinking that communism is a positive system:

"yet their aggression is more often concealed than open. they have fired no missiles; and their troops are seldom seen. they send arms, agitators, aid, technicians and propaganda to every troubled area. but where fighting is required, it is usually done by others--by guerrillas striking at night, by assassins striking alone--assassins who have taken the lives of four thousand civil officers in the last twelve months in vietnam alone--by subversives and saboteurs and insurrectionists, who in some cases control whole areas inside of independent nations." (kennedy)

president kennedy presents communism as cowardly, as a hidden and treacherous weapon that strikes from the shadows like thieves, he represents the system as not even being capable of showing and open and overt attack or confrontation. to finish up the response, he expresses that the system attacks even a country's idependence and freedom.

ccd puts the honeybee populations and crop health at risk.

the above detail from paragraph 2 supports the inference about honeybee.