Refer to the Graph Showing the Locomotor Activity of Drosophila

Refer to the graph showing the locomotor activity of Drosophila melanogaster flies that have been subjected to various gene-knockout experiments. What can be inferred about the normal function of gene C in the graph?

A) Gene C inhibits or regulates locomotor behavior; when the gene is knocked out, locomotor activity is elevated.
B) Gene C has little effect on locomotor activity.
C) Gene C has no effect at all on locomotor activity.
D) Gene C interacts with gene B in controlling locomotor activity.
E) There is insufficient data to make an inference.