[Solved] The knee-jerk reflex is controlled by interneurons in the A) synaptic gap. B) spinal cord. C) myelin sheath. D) parasympathetic nervous system. Nude Female's Picture: An image depicting a woman without clothes, often considered in contexts ranging from art and photography to issues of privacy and consent. Increased Heartbeat: A physiological response where the heart rate speeds up, which can occur due to various factors such as exercise, stress, or fear. Variable-Interval Schedule: is a type of reinforcement schedule in which responses are rewarded after unpredictable time intervals, leading to consistent and stable response rates over time. Fixed Amount of Time: A specific, unchangeable duration designated for a particular task or activity.