In Glenko Enterprises Ltd

In Glenko Enterprises Ltd.v.Ernie Keller Contractors Ltd.,[1994] 10 W.W.R.641 (Man.Q.B.) ,aff'd [1996] 5 W.W.R.135 (Man
C.A.) ,the court found in favour of the subcontractor plaintiff,stating interest was properly due on the outstanding account it was owed.Why did the court find in favour of the plaintiff?

A) Trade practices are a reliable way of implying terms into an existing contract.
B) Trade practices are automatically implied to parties' contractual obligations.
C) The defendant followed the industry practice of charging interest on its accounts.
D) The parties had a history of past dealings,which clarified their intentions.