Arepublic is a form of government where a)all citizens take an active role in decision making. b)military leaders represent the people c)a chief executive makes all the decisions. d)elected officials represent the people.

A republic is a form of government where...
d)  elected officials represent the people.  

A republican system of government allows people to elect their leaders.  The voters who elect these government officials do so because they believe the official will represent their views and voice their concerns.  A republic is a representative government; in other words, the citizens themselves do not make decisions and policies that directly affect the nation, but instead choose people to do this for them.  A republic is different from a democracy because in a democracy, the citizens DO make these decisions.  But today, most countries are too large for that to happen.  So, the people elect others to speak and act on their behalf.  The citizens that elect an official become that official's constituents.  The constituents can choose NOT to reelect this representative in the future, if they feel he/she did not do what was promised.  This type of government can be traced back to ancient Rome, and truly is one of the most important contributions that the Romans made to Western civilization.