Turnout design — the type of switch generally used on Indian Broad Gauge (B.G.) and Metre Gauge (M.G.) tracks is:

Introduction / Context:
Switch (point) design in railway turnouts influences manufacturing, maintenance, and running safety. Traditional Indian practice on B.G. and M.G. lines has standardized certain switch types for economy and interchangeability.

Given Data / Assumptions:

• Conventional turnout construction for B.G. and M.G. networks.
• Focus is on the common switch blade profile type.
• Not considering modern special-work variants for high-speed or heavy-haul corridors.

Concept / Approach:

The straight cut switch (with a straight planed switch blade against the stock rail) is the historically prevalent type on Indian B.G. and M.G. turnouts for standard speeds. Other switch types—articulated, undercut, or special curved—are reserved for special applications or newer designs and are not the general standard historically referenced in exam literature.

Step-by-Step Solution:

Verification / Alternative check (if short method exists):

Review of standard permanent way manuals indicates straight cut switch usage on conventional turnouts across much of the network historically.

Why Other Options Are Wrong:

Articulated or undercut switch types are special-purpose; over-riding describes a heel arrangement rather than standard planing; movable point frogs are different special trackwork items, not the typical switch blade form.

Common Pitfalls (misconceptions, mistakes):

Confusing modern high-speed curved switches with legacy general-use types; mixing frog designs with switch blade types.

Final Answer:

straight cut switch