Which of the Following Is the Best Definition of Cross-Rate

Which of the following is the best definition of cross-rate.

A) Money deposited in a financial centre outside of the country whose currency is involved.
B) International bonds issued in multiple countries but denominated in a single currency (usually the issuer's currency) .
C) Banks that make loans and accept deposits in foreign currencies.
D) The implicit exchange rate between two currencies (usually non-U.S.) quoted in some third currency (usually the U.S. dollar) .
E) Second borrower in currency swap. Counterparty borrows funds in currency desired by principal.