The question describes the act of purchasing goods from foreign countries ("offshore"). Let's analyze the options:
- (a) Management of merchandising: Merchandising involves planning and promoting the sale of goods, including product selection, pricing, display, etc. While it might involve deciding *what* to buy, "management of merchandising" doesn't specifically define the act of buying from other countries.
- (b) International sourcing (or Global sourcing, Offshore sourcing): This term specifically refers to the practice of procuring goods or services from suppliers located in other countries. This perfectly matches the description "buying of goods offshore, from other countries."
- (c) In-house planning: This refers to planning activities conducted within a company, which could relate to many aspects (production, marketing, finance). It doesn't define the act of buying from abroad.
- (d) Production plan: A production plan details how goods will be manufactured, including schedules, resources, etc. It might lead to a decision to source components or finished goods internationally if in-house production is not feasible or cost-effective, but it's not the act of buying itself.
The process of buying goods from other countries (offshore) is best described as
International sourcing. \[ \boxed{\text{International sourcing}} \]