Your judgement, please - Pt. 22

Retirado do site Chessbase.com.

A rook ending worth its weight in gold
05.11.2009 – The European Team Championship in Novi Sad witnessed an exciting final round in which the decision as to who would win the gold medal came as the result of a rook ending. Vugar Gashimov, White, absolutely had to win in order to secure the title for the Azerbaijani team. Daniel Stellwagen, Black, was fighting for a draw. In the position shown in our diagram, which move would you have chosen as Black? Think carefully.
GM Karsten Müller has analysed the decisive phase of the endgame Gashimov-Stellwagen for ChessBase Magazine Online.

Position after 70.f6