On Weekend Nights, a Large Urban Hospital Has an Average

On weekend nights, a large urban hospital has an average of 4.8 emergency arrivals per hour. Let X be the number of arrivals per hour on a weekend night at this hospital. Assume that successive arrivals are random and independent.
What is the probability of observing at least one emergency arrival?

A) 0.0477
B) 0.9523
C) 0.9918
D) Nearly 1