Question

15 in which sentence is the apostrophe used correctly?
a science is often used to help prove a persons guilt or innocence
b the killers dna led to their convictions.
c each persons dnas unique
d the eyewitness testimony was false

Explanation:

• Option A: The correct possessive form for "a person" (singular) is "person's", not "persons'".
• Option B: "Killers" is plural. The possessive form for a plural noun ending in "s" is to add just an apostrophe ('). So "killers' DNA" is correct as it shows the DNA belongs to the killers.
• Option C: The correct form should be "person's DNA" (showing the DNA belongs to a person). Also, the second apostrophe (in "DNA's") is mis - placed here as we are not talking about a contraction or a possessive of "DNA" in the wrong context.
• Option D: For a singular noun ending in "s" (like "eyewitness"), the possessive form is usually to add's. So it should be "eyewitness's" (although some style guides allow just an apostrophe for very common words ending in s, but "eyewitness" is not that common in this regard and the extra's is more standard).

Answer:

B. The killers' DNA led to their convictions.