Pat and Chris Are Vying for Jordan's Heart,and Both Value

Pat and Chris are vying for Jordan's heart,and both value winning Jordan's affection at $500.Jordan will choose between them based solely on which one spends the most money on gifts,movies,dinner and other enticements.Pat and Chris are fully aware of each other and of each other's spending.Spending must be in increments of $1 or more.
After each has spent $100,Pat says to Chris,"Let's be reasonable.I will promise to only spend just a little more on Jordan if you promise to do the same." Pat's statement

A) is credible because it is costly to fake.
B) is not credible because keeping the promise will not be in Pat's best interest.
C) is credible because both Pat and Chris make promises.
D) is not credible because the final decision rests with Jordan,not Chris.