Warby Parker is a for-profit company started by two friends who believe in giving back to the environment and to society. For every pair of eye glasses that it sells, Warby Parker donates a pair to entreprenuers in developing countries to generate economic opportunity. Warby Parker also uses 100% recyclable packing for its products. What is Warby Parker's business form?

a. General partnership.

b. Limited liability company.

c. Closed corporation.

d. Social enterprise.