Its linking 2 closely related independent clauses.
The Holocaust<span> was a mass murder of millions of people leading up to and </span>during<span> World War II.</span>
The best and most correct answer among the choices provided by your question is the second choice.
The sound techniques that are used in the poem is "<span>While the water was gently dripping, by my window, in the nipping November air."</span>
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