The best answer is: A Meat packing is a major industry.
Both the United States and Canada have significant meat packing industries as part of their agricultural sectors. However, option B as well (regarding forestry) might also apply to both countries due to their large forested areas. But "meat packing" is a more distinct and prominent shared industry that encompasses both nations.
Options C and D are not accurate; the U.S. has a federal republic system, while Canada has a parliamentary democracy. As for option D, while both countries have populations of African descent, the degree and context are different.
Therefore, based on the options provided, option A is the most fitting answer.