According to Brønsted-Lowry theory,
Acid is any compound which transfers or donate H⁺.
Base is any compound which accepts H⁺.
Example:
NH₃ + HCl → NH₄⁺ + Cl⁻
In Above Example NH₃ is acting as a Base, while HCl is acting as a Acid.
Result:
Option-E. (Acts as a proton acceptor) is the correct answer.