I’m not sure if this is even the right subject lol but anyways List 4 interesting facts about the element Cobalt

Cobalt was the first metal to be discovered since prehistoric times and the first metal with a recorded discoverer.

Cobalt-60 is used to create gamma rays which are used to treat cancer and to sterilize medical supplies.

Cobalt is one of only three naturally occurring magnetic metals, making it very useful for the uniquely calibrated magnets found in generators and hard drives. ...

Cobalt has been utilized by man for at least the last 2,600 years, providing blue pigments for glassware and ceramics.

Explanation:

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.

if it's not useful, feel free to report for mistake in answer.