a) Ileum is a highly coiled part
Explaination:
a) Small intestine is distinguishable into three regions, a ‘U’ shaped duodenum, a long coiled middle portion jejunum and a highly coiled ileum.
(b) A narrow finger-like tubular projection, the vermiform appendix which is a vestigial organ, arises from the caecum.
(c) Ileum opens into the large intestine.
(d) The wall of alimentary canal possesses four layers from outer to inner namely serosa, muscularis, submucosa and mucosa. Serosa is the outermost layer and mucosa is the innermost layer.