d) Old Faithful

Old Faithful, located in Yellowstone National Park, is the name of the famous geyser known for its regular eruptions. It is one of the most predictable geographical features on Earth, erupting almost every 90 minutes. Old Faithful was named in 1870 during the Washburn-Langford-Doane Expedition and has since become one of the most popular attractions in Yellowstone National Park. The geyser’s consistent performance makes it a must-see for visitors, and it is a symbol of the park’s extensive geothermal activity.