Final answer:
Lacking the specific trade-off data between trucks and balls, we can't calculate the exact opportunity cost for producing a second truck in terms of balls. Generally, opportunity cost refers to the value of the next best alternative forgone when making a choice.
Step-by-step explanation:
The question is asking for the opportunity cost of producing a second truck per day, assuming Tim is currently producing one truck per day using combination D. However, there appears to be insufficient information given in the question to directly answer what the opportunity cost of producing the second truck in terms of balls is. To determine the opportunity cost, we would need information about the trade-off between producing trucks and balls, similar to the given examples of opportunity costs between snowboards and skis, or the opportunity costs involving bus tickets and burgers.
As a general concept in economics, the opportunity cost is the value of the next best alternative that must be forgone as a result of choosing one option over another. In the examples provided, as the production of one good increases, the opportunity cost in terms of how much of another good must be given up also increases, which is the law of increasing opportunity cost.