The statement that is not true is Team C has its highest sales toward the beginning of the week. Option C
We have that;
Team A has its lowest sales toward the beginning of the week: This statement appears to be true. At the beginning of the week (Monday), Team A's sales are at the lowest point on the graph.
Team A has its highest sales toward the end of the week: This statement also seems to be true. Towards the end of the week (Thursday and Friday), Team A's sales rise to the highest points on the graph.
Team B has its highest sales toward the end of the week: This statement is true. Team B's highest sales occur on Thursday and Friday, which are towards the end of the week.
Team C has its highest sales toward the beginning of the week: This statement appears to be false. Team C's sales peak seems to be toward the middle or end of the week, not at the beginning.