A scientist examining the periodic table sees that the element magnesium (Mg) has the atomic number 12.

Based on this knowledge, what does the scientist immediately know is true about magnesium atoms?

A Magnesium atoms have 12 neutrons.
B Magnesium atoms have 6 protons and 6 electrons.
C Magnesium atoms have 12 protons.
D Magnesium atoms have 6 protons and 6 neutrons.