The upper part of the mantle is
Hard
OR
Soft

Hard

Explanation:

The upper part of the mantle is hard as it contains thick rock layers. The mantle's upper layer and the crust make up a brittle and rigid rock that's referred to as the Lithosphere.

The upper mantle starts below the Earth crust and then stops at the start of the lower mantle. We should note that the upper mantle results in the movement of the tectonic plates.

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

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wher is the rest of the question