Which statements are correct for ideal liquid-column oscillations in tubes?

Select all that apply

• Option A

  For a U-tube, the restoring head difference is twice the displacement of either free surface.

• Option B

  For an asymmetric V-tube, ω² = g(sinα+sinβ)/L.

• Option C

  For an upward-accelerating elevator, g is replaced by g+a in the U-tube formula.

• Option D

  Viscosity, if significant, would introduce damping and spoil ideal undamped SHM.