Read the passage below and choose the best answer to each question.
A geyser is the result of underground water under the combined conditions of high temperatures and increased pressure beneath the surface of the earth. Since temperature rises approximately one degree F for every sixty feet under the earth’s surface, and pressure increases with depth, water that seeps down in cracks and fissures until it reaches very hot rocks in the earth’s interior becomes heated to a temperature in excess of 290 degrees F. Because of the greater pressure, it shoots out of the surface in the form of steam and hot water. The result is a geyser.For the most part, geysers are located in three regions of the world: New Zealand, Iceland, and the Yellowstone National Park area of the United States. The most famous geyser in the world is Old Faithful in Yellowstone Park. Old Faithful erupts almost every hour, rising to a height of 125 to 170 feet and expelling more than ten thousand gallons during each eruption.
1. In order for a geyser to erupt,____________ .
