Why is the impact of the past physical modifications a concern for the present day, recognized as one of the Grand Challenges of Archaeology? Group of answer choices ancient building projects get in the way of modern building projects, and have to be torn down changes to the earth's surface in the past sadly used up resources (e.g., forests) that would otherwise be available for exploitation today past peoples erected large but very unstable structures that now pose many dangers past modifications continue to constrain and enable the intentions or desires of contemporary populations