The correct answer is Total exports for the China and United States.
The title which better suits the graph is the total export for the United States and China.
In 2011 the major export of China to United States was transport equipment and machInery which accounted for the total exports which followed minerals, rubber, and textiles.
United States in 2011 and 2012 their commonly export to China was agricultural products. For example, soybeans.
China is ranked the third country which United states exports goods to.