Which research method is the bizarro twin of the correlation study in terms of its strength and weakness, as compared to the strength and weakness of the correlation? "Bizarro" is a comic character best thought of as "evil Superman." Usage of the word reflects a mirror image/opposite relationship to whatever it is being compared; i.e. the correlation's strength is the ___'s weakness, and the correlation's weakness is the ___'s strength.
a. The experiment
b. The survey
c. Psychophysiological methods
d. The observation