Answer: D) They had not seen the experiment, yet they knew the results.
Step-by-step explanation: a conjunction is a an uninflected linguistic form used to connect clauses, phrases, words or sentences or to coordinate words in the same clause, for example: and, if, so, yet, but, or, nor, etc. In the given sentence we can see an example of a conjunction in the word "yet" it is joining two independent clauses: "they had not seen the experiment" and "they knew the results."