House sparrows in the northern part of North America are larger than those found in the southern regions. Which mechanism of microevolution is more likely to be responsible for this? A. founder's effect B. natural selection C. genetic drift

c

Explanation:

the truman doctrine was an american foreign policy whose stated purpose was to counter soviet geopolitical expansion during the cold war. it was announced to congress by president harry s. truman on march 12, 1947, and further developed on july 12, 1948, when he pledged to contain threats to greece and turkey.

i believe it would cause an increase of percipitation, though i could be wrong. so i would say b is the answer.