"What happens when you call a random store and start with a voluntary stutter? (W-w-what time do you close?)" I agree, if you do voluntary stuttering, then the intervention is the cause for the core behavior. In that case, both 1A and 1C are valid answers. I also overlooked 1C where we intervene by doing incorrect behaviors, specifically secondary behaviors that make the stutter worse. Blinking eyes could create stuttering, which is 1C, so your statement is indeed valid.