Which of the Following Is an Example of Triangular Arbitrage

Multiple Choice

Which of the following is an example of triangular arbitrage initiation?

A) buying a currency at one bank's ask and selling at another bank's bid, which is higher than the former bank's ask.
B) buying Singapore dollars from a bank (quoted at $.55) that has quoted the South African rand (SAR) /Singapore dollar (S$) exchange rate at SAR2.50 when the spot rate for the rand is $.20.
C) buying Singapore dollars from a bank (quoted at $.55) that has quoted the South African rand/Singapore dollar exchange rate at SAR3.00 when the spot rate for the rand is $.20.
D) converting funds to a foreign currency and investing the funds overseas.