A 70-year-old woman remains in asystole following 10 minutes of well-coordinated CPR, successful intubation, IV therapy, and three doses of epinephrine. There are no obvious underlying causes that would explain her cardiac arrest. At this point, it would be appropriate to:

A. attempt transcutaneous cardiac pacing.
B. defibrillate one time in case she is in V-Fib.
C. seriously consider ceasing resuscitative efforts.
D. transport at once with CPR continuing en route.