Vivian starts a fraud action against Dennis, a used car seller, arising from the sale of a car. Vivian asserts that Dennis advertised the car as new when in fact its odometer had been set back to zero from 10.000 miles. Before trial, Vivian took the deposition of Sam, Dennis's sales manager. During the deposition, Sam admitted that the seller sometimes turned back odometers on vehicles before sale. At trial, Dennis calls Sam, who testifies that he prepares all cars for Dennis and that no odometers were ever turned back while Sam worked for Dennis. On cross-examination, Vivian asks Sam whether he remembers having his deposition taken and stating that odom- eters sometimes were turned back. Sam admits to having had his deposition taken, but denies making the state- ment. Vivian wishes to read into evidence a portion of Sam's deposition transcript containing Sam's statement that odometers sometimes were turned back. Which of the following statements is most accurate? 

a. The portion of the transcript is admissible only to impeach Sam's credibility.

b. The portion of the transcript is admissible both to impeach Sam's credibility and to prove that the odometer was turned back 

c.  The portion of the transcript is inadmissible for either purpose because Sam is not unavailable.

d. The portion of the transcript is inadmissible for either purpose unless Dennis's lawyer cross-examined Sam at the deposition. 

e. None of the above.