What geographical challenges did the incas face?

(05.04 mc) how did the roman transportation system keep the empire strong? plz

What do most climatologists see as a major cause of rising global temperatures? a. earth's closer proximity to the sun due to its gravitational pull b. greenhouse gases produced by burning fossil fuels c. rising ocean levels caused by melting polar ice sheets d. water pollution cause by industrial waste

Why do people place so much importance on washington, dc?me