Answer:
F
Step-by-step explanation:
Helium (He) has 2 protons. Since the number of protons and electrons are the same, it also has 2 electrons. This means that it's first electronic shell is full and the particle is stable. There is no bonding between these atoms to form molecules.
Nitrogen (N) has 7 protons which is also 7 electrons. After filling the first shell (2), it will still have 5 electrons. The atom will share 3 electrons with another nitrogen atom. This will form 3 covalent bonds.
Oxygen (O) has 8 protons which is also 8 electrons. After filling the first shell (2), it will still have 6 electrons. The atom will share 2 electrons with another oxygen atom. This will form 2 covalent bonds.
Fluorine (F) has 9 protons which is also 9 electrons. After filling the first shell (2), it will still have 7 electrons. The atom will share 1 electron with another fluorine atom. This will form 1 covalent bond aka a single covalent bond.