3. Following Question 2, complexes based on what transition metals are used for this reaction as catalysts? (A) Fe and Co (B) Pd and Pt (C) Ni and Zn (D) Cr and Mn (E) Mo and Ru

1. The Nobel Prize in Chemistry in 2022 was awarded to click chemistry, or the azide-alkyne cycloaddition to connect two molecular fragments. For their initial discovery, what metal ion was required as a catalyst for this reaction to proceed at a milder condition? (A) Cu(I) (B) Zn(II) (C) Fe(II) (D) Fe(III) (E) Mo(II)