Which of the following phrases describes a manipulated variable? "Participants wrote down how many text messages they had sent the day before." "Researchers recorded whether participants volunteered to help the student in need or did not volunteer." "Participants were placed in the high tempo music condition, the low tempo music condition, or the no music condition based on which color card they randomly drew from a deck." "Researchers recorded the length of time participants took to complete the anagrams."

The correct answer is "Participants were placed in the high tempo music condition, the low tempo music condition, or the no music condition based on which color card they randomly drew from a deck."

Explanation:

Remember that manipulation is an attempt to affect thoughts, behaviors and feelings of participants. A manipulated variable is the one that we can change on purpose. It happens when a researcher alters the elements to see if the change has an impact on the experiment.