as the elements in period two on the periodic table are considered in succession from left to right, there is a decrease in atomic radius with an increase in atomic number. This may best be explained by the fact that

i think so it’s will be b yes i believe its

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.