Final answer:
The opportunity cost of producing a spaceship on the planet of Nevarro is the number of robots forgone. Since Navarro can produce 12,000 robots or 4,000 spaceships yearly, the opportunity cost of one spaceship is 3 robots.
Step-by-step explanation:
The question asks about the concept of opportunity cost within the context of economics. Opportunity cost represents the benefits of the next best alternative when a choice is made. In the case of the planet of Nevarro, the opportunity cost of manufacturing one spaceship is the number of robots that could have been produced instead. Given the information that Navarro can produce 4,000 spaceships or 12,000 robots per year, the opportunity cost of one spaceship is the number of robots that won't be produced as a result of producing one more spaceship. This is calculated through the ratio of the production capabilities of robots to spaceships.
To find the opportunity cost of one spaceship, we take the total number of robots that can be produced (12,000) and divide it by the number of spaceships (4,000), which results in an opportunity cost of 3 robots per spaceship. Therefore, the opportunity cost of manufacturing a spaceship in terms of forgone robots is not represented by any of the given multiple-choice options (a, b, c, or d).