Five jumbled up sentences, related to a topic, are given below. Four of them can be put together to form a coherent paragraph. Identify the odd one out

1. If all the firms in an industry were required to install specific pollution-prevention equipment, the government would need to set up a system to monitor compliance by each of the arms and to punish each violator.
2.Second-hand car markets for example are characterised by thousands of small firms, so there is much greater uncertainty about the industry standards that apply to them
3.It is far easier to regulate and administer an industry which has fewer firms operating within it, than to regulate one with several small firms.
4.However, this does not constitute an unequivocal case for large firms, because we have to weigh this against the costs of large monopolising industries.
5.This would give rise to challenges in administration, not to mention the costs, and there are limits to the penalty that can be imposed on a small violating firms.