hormonal induction of succus entericus is due to secretin alone or both secretin nd cholecystokinin? ...could u please provide with reasoning

Both Secretin and Cholecystikinin (CCK).

As we know , the complete digestion of food takes place in small intestine. The intestinal juice is known as succus entericus. It contains enzymes such as maltase dipeptidase, lipase nucleosidase, etc. It also contains mucus which in combination with bicarbonates released by pancreas provides alkaline medium and prevents intestinal mucosa from acid. 

The gastro intestinal hormones Secretin and Cholecystikinin (CCK) secreted by the intestinal mucosa allow the proper digestion of food through intestinal juice.

CCK is released in response to fat rich chyme and causes the contraction of gall bladder to release bile which in turn carries out the process of emulsification. 

Secretin is released when the chyme entering the intestine is highly acidic. Secretin stimulates pancreas to release  bicarbonates rich fluid so that proper ph is maintained for the functioning of other enzymes.