The concept of learned helplessness was formulated by Seligman to explain the ________.
a. Inability of dogs to attempt to escape avoidable shocks after having received inescapable shocks
b. Failure of dogs to learn to from prior mistakes
c. Ability of dogs to learn to help other dogs escape situations in which they are receiving uncontrollable shocks
d. Inability of dogs to learn to help other dogs escape situations in which they are receiving uncontrollable electric shocks