In context with the adaptations of the stomach in humans, fill in the blanks by choosing the correct option. The stomach in humans is lined with an extra layer of _____(i)_____ for better mixing and churning of food. It even has numerous folds called ____(ii)____ to increase the area of absorption with many inner mucosal secretory glands called _____(iii)____for the production of enzymes and has specially formulated ____(iv)____ to protect the walls of the stomach from the action of HCl.