Quality Control Engineers Fire Tiles Made with a New Material

Quality control engineers fire tiles made with a new material at three different temperature settings (1500ºF, 1800ºF and 2200ºF) and for four different times (2 hours, 6 hours, 10 hours and 12 hours) to determine the optimal parameter settings for firing that will result in tiles with high flexural strength.The number of treatments in this experiment is ________________________ .

A) 15
B) 12
C) 7
D) 4
E) 3