Unlike Early Studies of Motor Aspects of Stuttering, Current Research

Unlike early studies of motor aspects of stuttering, current research reported by Anne Smith concluded:

A) stuttering is "caused" by excessive muscle activation levels
B) stuttering is not "caused" by excessive muscle activation levels
C) tests of the respiration function of PWS have revealed lower than normal oxygen exchange levels that result in a slight hypertension limited to the muscles of respiration
D) the higher tension in the respiratory musculature of PWS results in insufficient air available for smooth speech production