The given graph shows the changes in the population of an insect found on a Jackfruit tree after four different sprayings of the same insecticide. What conclusion can you draw from the graph?

• A. The insecticide had no effect on the insects at all.                      
• B. The insect population had become resistant to the insecticide.
• C. The insect population increased as the wrong type of insecticide was used.
• D. The insecticide helped to reduce the number of insects permanently.