what is a molecular dipole moment?

dipole moments occur when there is a separation of charge. they can occur between two ions in an ionic bond or between atoms in a covalent bond; dipole moments arise from differences in electronegativity. the dipole moment is a measure of the polarity of the molecule.

explanation:

in inorganic chemistry -dipole moment ( μ ) is the measure of net molecular polarity, which is the magnitude of the charge q at either end of the molecular dipole times the distance r between the charges. μ = q × r.

beta decay is the answer

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.