Explanation
Choice D is the best answer. The convention being tested is the use of possessive determiners. The plural possessive determiner “their” agrees in number with the plural noun phrase “scientists William D. Phillips, Claude Cohen-Tannoudji, and Steven Chu,” thus indicating that the findings are those of these scientists.
Choice A: “It’s” is the contraction for “it is” or “it has,” which is not a possessive determiner.
Choice B: “They’re” is the contraction for “they are,” which is not a possessive determiner.
Choice C: The singular possessive determiner “its” does not agree in number with the plural phrase “scientists William D. Phillips, Claude Cohen-Tannoudji, and Steven Chu.”
✨ Expert's Tip ✨
A possessive determiner is a pronoun that is used to express belongingness. It shows who owns or possesses something.