Correct option is B
The distance between the running faces of the stock rail and the gauge face of the tongue rail measured at the heel of the switch is known as heel divergence. This distance is important for ensuring that the switch operates correctly and that trains can pass through the switch smoothly without derailing.
Flangeway clearance: Refers to the space provided to accommodate the flange of the wheel in the switch.
Throw of switch: Refers to the movement or travel distance of the switch blade.
Flare: Refers to the widening of the track or switch at the point where it diverges.
Therefore, the correct answer is (b) Heel divergence.
