What does the letter a b c and d represent in the punnet square

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 think that d. wind is the answer.   i missed the question when i answered a. currents.

hello

answer: collecting information/data

reason: the student is going around and asking people questions to collect data

i hope this