Final answer:
The most specific description for the level curve of the function f(x, y) = x² corresponding to c = 0 is a single vertical line.
Step-by-step explanation:
The level curve of the function f(x, y) = x² corresponding to c = 0 is a single vertical line. The level curve represents all the points (x, y) in the xy-plane where the function has a constant value of c = 0. For the given function, the level curve is represented by the equation x² = 0, which simplifies to x = 0. This means that all the points on the curve have x-coordinate equal to 0, and the y-coordinate can take any value.