Explanation:

The correct answer is option 'B', electrovalent bond.

An electrovalent bond, also known as an ionic bond, is formed between two atoms when one atom donates electrons to another atom. This transfer of electrons occurs between a metal and a non-metal.

Electrostatic Attraction:
- The electrostatic attraction refers to the force of attraction between positive and negative charges. In an electrovalent bond, this attraction occurs between positively charged ions (cations) and negatively charged ions (anions).
- The cation is formed when a metal atom loses one or more electrons, resulting in a positive charge. The anion is formed when a non-metal atom gains one or more electrons, resulting in a negative charge.
- The electrostatic attraction between these oppositely charged ions holds them together and forms an ionic compound.

Characteristics of Electrovalent Bonds:
1. Electrovalent bonds involve the transfer of electrons from one atom to another.
2. The atoms involved have a significant difference in electronegativity, resulting in the formation of ions.
3. The resulting compound is typically composed of a lattice structure, where the positive and negative ions are arranged in a repeating pattern.
4. Electrovalent compounds are usually solids at room temperature and have high melting and boiling points due to the strong electrostatic forces between the ions.
5. Electrovalent compounds are often soluble in water and conduct electricity when dissolved or melted, as the ions are free to move and carry charge.

Options Explained:
a) Single Covalency: This term refers to the sharing of one pair of electrons between two atoms in a covalent bond. It is not applicable to the electrostatic attraction between positive and negative ions.
b) Electrovalent Bond: This term accurately describes the bond formed as a result of the electrostatic attraction between positive and negative ions.
c) Covalent Bond: Covalent bonds involve the sharing of electrons between atoms, but in an electrovalent bond, there is a transfer of electrons.
d) Coordinate Bond: This type of bond occurs when one atom donates both electrons in a shared pair to another atom. It is not applicable to the electrostatic attraction between positive and negative ions.

Therefore, the correct answer is option 'B', electrovalent bond.