To test the effectiveness of plant fertilizer, groups of plants are grown with different types of fertilizer. A control group of
plants would
A not be given any fertilizer.
B
be grown with a mixture of all the fertilizers.
C
not be needed unless the results were unclear.
D
be grown in a different location from the other groups.

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.

the most common energy conversion is from kinetic energy to potential energy, and then from potential energy to kinetic energy.

later on comes the heat energy, mechanical energy, and other energy conversions.

this energy conversion is so common that we can find it in our day to day lives as well.

- one of the most common energy conversions involves the changing of potential energy to kinetic energy or kinetic energy to potential energy