What must happen before chemical reaction can begin

Read the scenario below and answer the question that follows. hallie is reading a novel in the library when susan, her best friend, slumps down in a chair next to her. susan doesn't say anything, but hallie knows that susan is upset because she is slumping in her seat and rolling her eyes. a psychologist would explain that hallie is interpreting her friend's emotion based on a. the behavioral component of emotion b. her friend's ability to regulate emotion c. the verbal component of emotion d. the physiological component of emotion select the best answer from the choices provided a b c d

_tissues respond quickly to outside stimuli a) epithelia b)nervous c)muscular d)muscular and nervous

They live on every continent except antarctica