Given a text T, and several options, according to the question posed in the text T to choose the most appropriate option from the options as the answer, please directly output the most appropriate option, do not need to output the explanation.

A one-year zero-coupon bond yields 4.0%. The two- and three-year zero-coupon bonds yield 5.0% and 6.0% respectively.
Given the yield curve for US Treasury zero-coupon bonds, which spread is most helpful pricing a corporate bond? The:
Option A:Z-Spread.
Option B:TED spread.
Option C:Libor–OIS spread.

Answer: A