The correct statement regarding ethane conformation is:

• A
  Rotation around carbon-carbon bond in ethane molecule is not possible,because ethane molecule contains a pi $(\pi)$ bond between the carbon and carbon and ethane has very low melting point.
• B
  Rotation around carbon-carbon bond in ethane molecule is not possible,because ethane molecule contains both sigma $(\sigma)$ bond,and pi $(\pi)$ bond between the carbon and carbon.
• C
  Rotation around carbon-carbon bond in ethane molecule is possible because of cylindrical symmetry of sigma $(\sigma)$ bond between carbon-carbon atoms.
• D
  Rotation around carbon-carbon bond in ethane molecule is not possible,because ethane molecule contains both sigma $(\sigma)$ bond and pi $(\pi)$ bond between the carbon and carbon and ethane has very high boiling point.