What was the purposes of “killing centers”?

The Nazis established killing centers for efficient mass murder of the Jews. About 2,700,000 Jews in the killing centers were killed.

The two parties signed the Hay–Bunau-Varilla Treaty. It gave the United States a ten-mile strip of land, all the rights to construct and administer a canal, and the right to protect the canal. In return, the Panamanians received $10 million and an annual rent of $250,000.

so the closest thing you have is C.