Final answer:
All three options - vandalism, looters, and urban sprawl - are threats to archaeological sites, making the answer D. 1, 2, and 3. These threats can cause significant damage, disturbing both the physical integrity and historical context of sites, contrasting sharply with proper archaeological practices.
Step-by-step explanation:
The threats to archaeological sites include vandalism, looters, and urban sprawl. Thus, the correct answer to which threats impact archaeological sites is D. 1, 2, and 3. Vandalism can consist of actions such as carving initials into ancient walls, painting over historic artwork, and generally defacing the site. Looters may dig up and steal cultural artifacts, often for private collections or sale, which is illegal and destructive to the historical context of the site. Urban sprawl contributes to the degradation of archaeological sites through construction and the expansion of developments which may damage or entirely remove historical sites. These threats affect sites like Cascadia Cave, which has suffered from the presence of tourists and early archaeologists, both disturbing the archaeological context and causing physical damage to the site. Controlled excavations by qualified archaeologists aim to minimize damage and preserve as much context as possible for future research and interpretation. The care taken during legitimate archaeological excavations contrasts sharply with the destruction caused by unauthorized digging and the pressures of urban expansion.