Taye receives services from three different RBTs at an ABA c…

Taye receives services from three different RBTs at an ABA clinic. Taye has only a few items she prefers and typically only responds to edible items. Taye often responds to RBT Alicia’s instructions, as she always delivers preferred edibles following each response. Taye rarely responds to RBT Brandy’s instructions because she often forgets to deliver preferred edibles following each response. Taye is also less likely to respond during afternoon sessions following lunchtime than he does during morning sessions. Which of the following is functioning as an SΔ in this scenario?