D) Wayne felt homesick for his family while in Vietnam, yet he tried to enjoy his time overseas
<span>The sentence that does not contain any errors is D. Whose muddy shoes are these on my clean kitchen floor? This is because the possessive pronoun whose is correctly used here. In A, it should be Greg's, and not Gregs'. In B, it should be actresses' families, and not actresses families'. In C, it should be it's, because that means it is, and not its, which is a possessive pronoun (the dog wagged its tail).</span>
There are several primary sources that you might use, here are a few examples:
A diary written by a soldier during a battle.
Medical records of war doctors from the battle.
newspaper clippings about the battle (and published at the time of the battle).
Speeches of famous generals from the battle.
Yes, commas are used for clauses that help to provide a fuller picture, even when not necessary. Dashes can be used for a similar purpose as they are used here, but i don't believe it's appropriate in this sentence. Parentheses can only be used for information that can be completely written off without having any effect on the sentence.