Amy is experimenting to see how a truss (a type of support) can strengthen a bridge. Amy builds several models of bridges out of toothpicks. Each model has a different number of trusses.

Amy suspends each model between two desks. She then adds lead weights to each bridge, one-by-one, until the bridge breaks. In the chart below, Amy recorded how many lead weights each bridge held before breaking.
What is a valid conclusion that Amy can draw from her experiment?

the answer to your question is b

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.

chert is a sedimentary rock composed of microcrystalline or cryptocrystalline silica. with this little bit of information, you can come to the conclusion that your answer is c.  

explanation:

sodium i think the chemical element of atomic number 11, a soft silver-white reactive metal of the alkali metal group.