.......... is the longest part of the alimentary canal

The tiny intestine is the alimentary canal's longest and narrowest tubular section. The Duodenum, Jejunum, and Ileum are the three sections of the small intestine.

The stomach empties into the duodenum, which is a short (20 to 25 cm long) and broader anterior section.

The jejunum is a coiled intermediate section that measures 0.8 to 1.5 metres in length, while the ileum measures 3 to 3.5 metres.

As a result, option B is the right answer.

Hence the correct answer is option B : Ileum