The most important attribute of earth is that it is a(n).
system, providing the precise combinations of objects and characteristics
to permit the existence of life.

The most important attribute of Earth is that it is a(n) life-support system, providing the precise combinations of objects and characteristics  to permit the existence of life.

Explanation:

The earth is made up of various systems that interact with each other and sopport the life.

The systems are the biosphere (it is composed of living beings), the hydrosphere (is composed of water), the atmosphere (contains the air), and the lithosphere (it is composed of the earth's layers). A change in one of the systems would change the others. The interrelation between the systems makes our planet so unique, without one of them, the life of the earth would not exist.

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