Answer:
The first excerpt is an add-on sentence.
Explanation:
"The researchers used several methods for testing their data the article explains them all." is a run-on sentence. There are two separate parts to this sentence:
1) "The researchers used several methods for testing their data" is one statement that stands on its own. The researchers used several methods for testing" is statement that tells the reader a fair amount of thought and work went into the publication. It should be a stand-alone sentence.
2) The next portion"the article explains them all." is also a stand-alone statement. The reader now knows that the methods will be explained in the article.
It should read:
The researchers used several methods for testing their data. The article explains them all.