Symptoms of posttraumatic stress disorder must last at least for a diagnosis to be made

Recent research has indicated that many adolescents

feel increasingly invincible over time. feel situationally invincible. are pressured to feel invincible. do not feel invincible.

In an experiment, a researcher manipulates one variable to see how it affects a second variable. The manipulated variable is called the:

a) dependent variable. b) experimental variable. c) independent variable. d) placebo.