Ice Cores Taken in Greenland Indicate That, Between 10,300 and 10,100

Ice cores taken in Greenland indicate that, between 10,300 and 10,100 years ago, the world experienced:

A) a sudden and dramatic return to colder temperatures during a period of warming
B) rapid sea level rise and resulting catastrophic flooding of coastal regions
C) massive volcanic activity and a resulting "nuclear winter"
D) all of the above