How red blood cells different to animal cells

By contrast, the red blood cells of mammals lack nuclei and other internal structures found in most animal cells. This simplification allows mammal red blood cells to carry more gas-transporting proteins and to squeeze through smaller blood vessels.

Explanation:

answer; i do believe the correct answer is (river); /// good luck

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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