Scenаriо: During а clinicаl evaluatiоn, a Kinesiоlogy student is observing a patient performing a rapid, passive stretch of the hamstrings. The student notices an immediate, involuntary contraction of the hamstrings (the stretch reflex). Later, during a heavy isometric maximum voluntary contraction, the patient’s muscle suddenly "gives way" or relaxes to prevent injury. Which of the following correctly identifies the sensory receptors responsible for these two distinct responses?