What is a controlled experiment? A. An experiment with only experimental variables
B. An experiment with no variables
C. An experiment with no controlled variables
D. An experiment with one dependent variable and one experimental
variable

The answer is d) by requesting advice on science internet sites

Your answer would be false

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Jenny and fred both play a long note on their trombones. a stationary observer hears the sound increasing and decreasing repeatedly in loudness. which of these must be true? the sound waves from the two trombones have slightly different frequencies.the sound waves from the two trombones have the same frequency.the sound waves from the two trombones have slightly different amplitudes.the sound waves from the two trombones have the same wavelength.the sound waves from the two trombones have slightly different velocities.  lolthe answer is          the sound waves from the two trombones have slightly different frequencies.