The statement that offers the best critique of how humans have impacted the environment through agricultural activities is:
"Human agricultural activities have always impacted the physical environment."
This statement acknowledges the longstanding relationship between human agriculture and environmental change, emphasizing that agricultural practices have historically played a significant role in altering ecosystems, landscapes, and biodiversity long before the modern era. The other statements either downplay this impact (such as suggesting that slash and burn does not have repercussions now) or misrepresent the timeline of human-environment interactions.