High-performance EMS systems typically use a fractile response time standard, in which:

A) a significant fraction of all responses must be achieved within an established time.
B) the ambulance must arrive at the scene within 8 minutes in 50% of all dispatches.
C) turnaround time for the entire call should be no more than 1 hour in 90% of all calls.
D) medics must be in the ambulance and en route within 2 minutes of being dispatched.

Answer: A) a significant fraction of all responses must be achieved within an established time.