Step 1: Check Option (A).
On an equipotential surface, the potential is constant. Therefore, no work is required to move a test charge on the surface, since work done is
\[
W = q \, \Delta V = 0
\]
Hence, Option (A) is incorrect.
Step 2: Check Option (B).
At a given point in space, the potential has a unique value. Since an equipotential surface is defined as the locus of all points having the same potential, only one equipotential surface can pass through a given point.
Thus, Option (B) is correct.
Step 3: Check Option (C).
By definition, an equipotential surface is one where the potential remains constant everywhere.
Thus, Option (C) is correct.
Step 4: Check Option (D).
Electric field lines are always perpendicular, not parallel, to equipotential surfaces. This ensures no work is done in moving a charge along the surface.
Thus, Option (D) is incorrect.
Step 5: Conclusion.
The correct statements are (B) and (C).
\[
\boxed{\text{Correct Answer: (B) and (C)}}
\]