Answer:
B) the uneven distribution of gains and losses from free trade.
Step-by-step explanation:
One of the most important reasons why governments impose trade barriers is to protect domestic jobs (and domestic industries). We are part of a society (country), and society's most important component is people, not money. Generally the economic gains of free trade are larger than the economic losses, but the economic losses hurt the most.
Imagine if no trade barriers actually existed, how many millions of jobs would be lost in the US. Trade barriers are nothing new, the current president didn't invent them. He just incinerated them.
How does a leader tell the people that 10 or 20 million must lose their jobs and probably will not be able to find any similar jobs in the future just because the rest of society will benefit from cheaper products. The lives of 20 million households (50-80 million people) would be destroyed, while 280 million people would benefit.
The amount of harm done to the people that lose their jobs is much greater than any individual benefit.