The correct answer to this open question is the following.
Although you did not include any reference or options, we can say that the phrase that could indicate you are working with a primary source is the one that exactly transcribes what the author says. This makes the source as a valid one, using proper citation.
Let's have in mind that a primary source is information recorded by people who lived in the time of the event and wrote a testimony, a letter, took photographs or videos, depending on the epoch. It also could be news or interviews with characters that were part of those events. That is why, you have to quote the source as it delivered the information, using proper citations and giving the right credit to the sources.
Generally speaking, it was difficult for American ground forces to clear areas of guerrillas because "The guerrillas hid themselves from American forces" and "<span>The guerrillas fled while the ground forces were in their area". </span>
<span>The Fifth Amendment to the United States Constitution provides that no person shall be subject for the same offence to be twice put in jeopardy of retrial after acquittal, conviction, multiple punishment, and or retrial after certain mistrial. Hence, in essence, this amendment protects a person getting into jeopardy again for the same offence which had initially led him into jeopardy.</span>
The best option from the list in terms of a factor that contributed to planters using enslaved Africans as a labor source was that "<span>C. England entered the Atlantic slave trade".</span>
