PT 61 S2 Q20

When people show signs of having a heart attack anelectrocardiograph (EKG) ... ...

Which one of the following, if true, most weakens the argument?
(A) Experts agreed that the cardiologist made few obvious mistakes in reading and interpreting the EKG data.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Complete Section: LR-A, Oct. '10 LSAT (PT 61 Sec. 2)