Which of the following statements is true about enzymes? A. They are used up in the reactions they catalyze.

B. They slow down or prevent chemical reactions from occurring.

C. They speed up reactions
lowering the activation energy.

D. They supply the energy needed for a reaction to occur.

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