From 0 - 7 on the pH scale, substances are said to be acidic. At 7, the substance is said to be neutral. From 7 - 14, substances are basic.
Lime is a basic substance. Therefore, when it is added to the soil, one should expect that the soil becomes more basic. On the graph, this should be represented by the line increasing in pH. As such, the point at which lime was added was most likely Point B.
