Which best describes fetal development? The heart beats and is heard during the first trimester.
The heart beats and is heard during the second trimester.
The heart beats during the first trimester, but is heard in the second trimester.
The heart beats during the second trimester, and is heard in the third trimester.

what image you forgot to include it.

the atomic number of magnesium is 12. its nucleus must contain 12 protons and no electrons. the atomic number of an atom is determined by the number of protons.

magnesium is an electrolyte injection commonly used to treat low magnesium levels in your blood. it is also used to prevent or control seizures in women with preeclampsia or eclampsia.