Which of the ALJ’s findings against the coal company will be hardest to overturn on appeal? Why?

This case concerns a coal miner who was dismissed by his employer, allegedly because he was unable to perform his job anymore due to injuries. The coal miner asserted that he was actually dismissed in retaliation for his complaints against the company for violating Mine Safety & Health Administration regulations. After you have read the decision in the case, please answer the following questions:
Where in the administrative law judge’s [ALJ’s] decision does she talk about how she evaluated the evidence and the witnesses?
Which of the ALJ’s findings against the coal company will be hardest to overturn on appeal? Why?