Craters visible on the moon's surface provide further evidence of
a) frequent asteroid impacts.
b) periodic volcanic eruptions.
c) frequent landings of spacecraft.
d) the long-ago presence of ice on the moon.

it is the most commonly accepted one

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.