You Take a Human Smooth Muscle Cell and Block the Release

You take a human smooth muscle cell and block the release of calcium from the sarcoplasmic reticulum. What effect does that have on contraction of that smooth muscle cell, and why?

A) Contraction is completely blocked because calcium binding to troponin is required for contraction.
B) Contraction is completely blocked because calcium binding to calmodulin is required for contraction.
C) Contraction still occurs because Ca²⁺ can enter the cell directly through Ca²⁺ channels in the plasma membrane and bind to troponin.
D) Contraction still occurs because Ca²⁺ can enter the cell directly through Ca²⁺ channels in the plasma membrane and bind to calmodulin.
E) Contraction still occurs because contraction in smooth muscle is completely independent of Ca²⁺ levels.