Choose the correct description for the following sudoku solving technique: Hidden Single

A) When only one position remains for a specific digit in the entire puzzle, place that digit there.

B) For one digit, two rows that have candidates in exactly the same two columns form a rectangle; all other instances of that digit in those columns can be eliminated.

C) A three-cell formation where the pivot has three candidates and the outer cells share two of them. The third candidate is eliminated from any cell that sees all three.

D) Within a row, column, or box, if a digit can go in only one cell, that cell must contain it, even if other candidates exist.
