The correct answer is A. Drawings.
Drawings are the amount of money that a business owner takes out of the business for personal use. When a business owner takes out more money than they put in, the capital of the business decreases.
Income is the money that a business makes from its sales. Gains are the profits that a business makes after it has paid its expenses. Fresh capital is the money that a business owner invests in the business.
All of these things can increase the capital of a business, but only drawings can decrease it.