Which of the Following Statements Is LEAST-Likely True

Which of the following statements is LEAST-Likely true?

A) Friction occurs between the piston rings and cylinder walls.
B) Low-tension piston rings were introduced in the mid-1980s to improve fuel economy.
C) Compression rings account for about 60% of the total drag on a cylinder wall, and the oil ring accounts for 20%.
D) Cast iron rings are used in re-ring jobs when the cylinder walls have not been re-bored.