Which statement best describes a characteristic of a Lewis base?

• A. It donates an electron pair to form a coordinate covalent bond.
• B. It donates a proton ($H^{+}$) to another species.
• C. It increases the concentration of $H^{+}$ in water.
• D. It accepts an electron pair to form a coordinate covalent bond.

Answer: (A)

Verified step by step guidance

1. Recall the definition of a Lewis base: a Lewis base is a species that donates an electron pair to form a bond.
2. Understand that a Lewis acid is the species that accepts an electron pair, while a Lewis base donates it.
3. Recognize that donating a proton (H\(\textsuperscript{+}\)) or increasing H\(\textsuperscript{+}\) concentration relates to Brønsted-Lowry acids and bases, not Lewis acids and bases.
4. Identify that the correct characteristic of a Lewis base is donating an electron pair to form a coordinate covalent bond.
5. Therefore, the statement 'It donates an electron pair to form a coordinate covalent bond' best describes a Lewis base.