In the following passage some of the words have been deleted. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.

Intriguingly, those who (1) ______ the psychobiotic diet reported they felt less stressed compared (2) ______ those who followed the control diet. There was also a direct correlation between how strictly (3) ______  followed the diet and their perceived stress levels, with those who (4) ______ more psychobiotic foods during the four - week period reporting the (5) ______  reduction in perceived stress levels.