Assertion. On receiving action potential via T-tubules, the sarcoplasmic reticulum releases `Ca^(++) ` into the sarcoplasm.
Reason. `Ca^(++)` uncover the active site of actin myofilament, allowing a meromyosin head to join this site.
A. If both A and R are true and R is the correct explanation of A .
B. If both A and R are true but R is not the correct explanation of A.
C. If A is true but R is false.
D. If both A and R are false.