Answer:
None of the statements are entirely true.
The first statement is referring to the concept of marginal benefit (MB) and marginal cost (MC) analysis, which can be used to guide decision-making. However, it does not apply in this case because it is not clear what the benefits and costs of the proposed GMO usage reduction would be, and how they would be distributed among the ASEAN nations.
The second statement is not entirely accurate because developing nations' objections to the proposed GMO usage reduction cannot be automatically equated with the free-rider problem. The free-rider problem occurs when some individuals or groups benefit from a public good without contributing to its provision, but it is not clear that this is the case here.
The third statement is not entirely accurate because there may be different levels of GMO usage that are efficient depending on the specific circumstances and trade-offs involved. Furthermore, individual nations may not have a clear incentive to cut GMO usage if they perceive that the costs of doing so outweigh the benefits or if they believe that other nations will not comply with the agreement.
Overall, the issue of GMO usage reduction in ASEAN is complex and requires careful consideration of the trade-offs involved, including economic, social, and environmental factors.