From Venezuela to Argentina, oil's steepest plunge in three years is reverberating through a region that accounts for the largest crude reserves outside of the Middle East. Venezuelan oil bond yields jumped, American depositary receipts of Petroleo Brasileiro SA, YPF SA and Ecopetrol SA plunged and the Colombian peso fell the most in five years after the 12-nation OPEC opted against measures to prop up crude prices Nov. 27. Brent is down 13 percent this week.