In a covalent bond

A. electrons are shared between a limited number of atoms
B. chains or sheets of atoms are held together by weak forces
C. electrons are shared between all atoms in a solid mass
D. atoms are joined by electrical charges

A. electrons are shared between a limited number of atoms

Explanation:

Covalent bond -

Covalent bond is the bond which is formed with the sharing of the electrons between the two atoms which are taking part in the bond. It is generally formed between the atoms with similar electronegativity values.

It is the bond which is generally occurs within non metals as they share electrons to complete their octet.

The difference in the electronegativity values of the atoms involving in a covalent bond must not exceed the value of 1.7 .

Hence , from the above information ,

The correct option is a.