The correct answer is: B. Reasonably long term.
The going concern concept assumes that the business will continue to operate for the foreseeable future. This means that the business will not be liquidated or sold in the near future. The going concern concept is important because it allows businesses to make long-term plans and investments.
Option A is incorrect because it is not realistic to assume that a business will continue to operate indefinitely. Businesses can face a variety of challenges, such as economic downturns, changes in technology, and competition from new businesses.
Option C is incorrect because it is too short a period of time to make long-term plans and investments. Businesses need to be able to plan for at least several years into the future.
Option D is incorrect because it is not a realistic period of time for a business to operate. Businesses typically operate for much longer than one year.