Answer : The correct option is, Two atoms share two electrons.
Step-by-step explanation:
Ionic bond : It is defined as the bond that is formed by complete transfer of electrons from one atom to another atom.
That means, the atom which looses the electron is known as electropositive atom and the atom which gains the electron is known as electronegative atom.
The ionic bond is usually formed between a metal and a non-metal.
Covalent bond : It is defined as the bond which is formed when sharing of electrons takes place between the atoms.
This is usually formed between two non-metals.
As per question, for making a single covalent bond the two atoms share their two electrons.
Hence, the correct option is, Two atoms share two electrons.