Which of the following sentences from the passage BEST supports the idea that the citizens of Pompeii were unaware that the volcano existed?

A. "The extreme heat underground has dried up streams."
B. "Vesuvius has been dormant for 1,500 years..."
C. "Small earthquakes have jolted the city, a sign of growing strain on the land."
D. "Two powerful explosions, seconds apart, shatter the sky."