Cu, Cd, Au, and Co are all transition metals.
Work Step by Step
Transition metals all belong inside the d-block. Those are the only 4 elements listed that belong to the d-block making them the correct answers.
You can help us out by revising, improving and updating this answer.Update this answer
After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.