Kristopher is extremely sure of himself. He gets angry when his teachers or friends try to offer him constructive criticism and is extremely impulsive. When he takes a test in school, rather than studying, he bases his answers on "what feels correct." Which of the following statements best explains Kristopher's behavior? a. He is lacking in effortful control. b. He is concealing low self-esteem. c. He is being abused at home. d. He is being shunned by his peers.