A plausible consequence of the Bronze Law setting a maximum wage for porters at $0.10 a day, while the market wage is $0.08 a day, would be that porters would travel less quickly than they otherwise would.
This is because the wage is already at a level that is below the perceived minimum needed for survival, which could lead to decreased motivation and productivity among porters. If they are not compensated adequately for their work, they may not exert as much effort, resulting in slower transportation of goods.
The other options are less likely: "Nothing unusual would happen" is unlikely because the law creates a distortion in the labor market; "Unemployment for porters would decrease" is also unlikely, as the wage cap could lead to a surplus of labor; and "Porters would transport items they normally would not" does not directly relate