Carbon-Carbon Double Bonds Do Not Freely Rotate Like Carbon-Carbon Single $\pi$

Multiple Choice

Carbon-carbon double bonds do not freely rotate like carbon-carbon single bonds. Why?

A) The double bond is much stronger and thus more difficult to rotate.
B) Overlap of the two 2 p orbitals of the $\pi$ bond would be lost.
C) The shorter bond length of the double bond makes it more difficult for the attached groups to pass each other.
D) Overlap of the $\mathrm{sp}^{2}$ orbitals of the carbon-carbon $\sigma$ bond would be lost.