The correct answer to the question is option 4 - "not easily worn down." Granite and quartzite have an upstanding look because these rocks are resistant to erosion and do not easily wear down. They are composed of durable minerals that make them hard and strong, which means they can withstand various forces of erosion such as wind, water, and ice. These rocks are not easily broken apart or weathered by mechanical processes such as abrasion or impact. As a result, they retain their shape and form prominent features like peaks and ridges, creating an upstanding appearance. It is important to note that while option 2 - "these rocks are resistant to all kinds of erosion" is true, option 4 provides a more specific and accurate explanation for the upstanding look of granite and quartzite.