駅に着い___、電話してください。
Q. Which form creates 'when/once you arrive at the station'?
Translation
Please call me when you arrive at the station.
Explanation
たら works for one-time 'when/once X happens' situations and is the most natural before a request (〜てください). と states automatic results and cannot be followed by a request; ば and なら also resist direct requests in this pattern.