What were some of the ways in which the Chinese government successfully apprehended illegal salt dealers?

Please answer the following questions using 5-7 sentences for each answer based on the article below. 1. What were some of the ways in which the Chinese government successfully apprehended illegal salt dealers? 2. Why is salt the food of choice in iodine fortification policies ? The link to the case study article :

https://www.cgdev.org/sites/default/files/archive/doc/millions/MS_case_15.pdf