The graph shows that he sold 10 jars of blueberry jam the first year and 18 the second year, for an increase of 8 jars. This is the largest increase of any of the flavors.
Grape is incorrect. This is the jam he sold the most of, but it is not the largest increase. Peach is incorrect. He sold more peach jam the second year, but his sales increased by only 4, which is less than the increase for blueberry. Strawberry is incorrect. He sold less strawberry jam the second year, not more.