How many protons, neutrons and electrons are contained in one atom of\[_{19}^{39}K\]?

• A. \[19\] protons \[+\,\,20\] neutrons \[+\,\,19\] electrons
• B. \[19\] protons \[+\,\,20\] neutrons \[+\,\,20\] electrons
• C. \[20\] protons \[+\,\,19\] neutrons \[+\,\,20\] electrons
• D. \[20\] protons \[+\,\,20\] neutrons \[+\,\,19\] electrons