Fill in the blank with correct option. An alert and vigilant public is…

A democracy is a system in which governing authority is derived from, and exercised on behalf of, the citizens themselves — through free elections, freedom of expression, the right to information, and mechanisms that hold elected representatives accountable. Its defining feature is that this authority remains legitimate and effective only for as long as the citizenry actively participates in and monitors it.

The statement describes exactly this condition: a public that is alert and vigilant — questioning government decisions, exercising the right to vote and to information, and holding representatives accountable. This is precisely what sustains and strengthens a democracy; without an engaged citizenry, democratic institutions weaken and government action escapes public scrutiny.

Contrast with the other systems named:

• Monarchy — authority passes by hereditary succession within a ruling family; its continuity does not structurally depend on an alert public.

• Oligarchy — governing power is concentrated in a small ruling group or elite, so the system's stability rests on that group retaining control, not on broad public vigilance.

• Autocracy — power is centralised in a single ruler with minimal institutional checks; such rule typically limits, rather than depends on, an alert and questioning public.

Since only a democracy structurally depends on an alert and vigilant citizenry to remain strong and accountable, "Democracy" correctly completes the blank.