The Ring of Fire contains approximately 850–1,000 volcanoes that have been active during the last 11,700 years (about two-thirds of the world's total). The four largest volcanic eruptions on Earth in the last 11,700 years occurred at volcanoes in the Ring of Fire.
At the start of a drought, groundwater may not be noticeably lower (not B). Only aquifers near the ocean may become contaminated with salt water (not C). And it is definitely not D.