A Treadle bar is used for

ANS:A - Interlocking points and signal

A treadle bar is generally installed at the point of switching the track system. A treadle bar is an electronic circuit that is activated only when the train is passing over it.

As soon as the train starts passing over it, the treadle bar disables the function of switching the track, because switching a track when the half of the train has already crossed it will lead to an accident.