#MCAT<https://www.facebook.com/hashtag/mcat?source=feed_text&story_id=738547456308685> Question of the Day:

Which of the following structures is responsible for the release of calcium ions?

A. Neuron
B. Sarcomere
C. Intercalated disks
D. Sarcoplasmic reticulum
E. Endoplasmic reticulum