"John and Sam decide to sign a contract for the sale of John's vintage Harley Davidson motorcycle, incorporating all terms to which they have agreed.The contract is drawn up by John.Sam reads it and agrees.Before Sam can sign it, John substitutes a different version to which Sam has not agreed.If Sam signs the contract, this would be"

a. fraud in the execution

b. fraud in the inducement

c. negligence

d. concealment