Thanks. OK so on point C, you drop on the back of the green, so not having to cross the pond a second time, IF, the first ball crossed it, touched the far side, but rolled back into the pond.If it is a red PA, the options are: a) S&D b) from reference point of point of last crossing, lateral relief within 2CL no nearer the hole than the reference point and outside the PA or c) BACK on line from the line from the reference point to the pin - which means behind the PA. Heading to the opposite side of the green is not an option.
If there is no area outside the PA that meets the restrictions in b), then only a) and c) are options, unless the Committee has established a DZ.
But not if the first shot failed to carry the pond.