Answer:
B. sarcoplasmic reticulum ; sarcoplasm
Explanation:
A neural signal is the electrical trigger for calcium release from sarcoplasmic reticulum into the sarcoplasm. Electrical signals, called action potentials, travel along the neuron's axon connecting to individual muscle fibers at a neuromuscular junction. Neuron action potentials cause the release of neurotransmitters from the synaptic terminal into the synaptic cleft, where they can diffuse across the synaptic cleft and bind to a receptor molecule on the motor end plate.
