Final answer:
The lamina propria is contained within the b) mucosa layer of the alimentary canal, contributing to nutrient transport and immune defense.
Step-by-step explanation:
The tunic of the alimentary canal that contains the lamina propria is the mucosa. The mucosa is the innermost layer of the alimentary canal, which includes the lamina propria, an area of loose connective tissue. The lamina propria is significant, as it contains blood and lymphatic vessels that transport absorbed nutrients, as well as clusters of lymphocytes, which comprise the mucosa-associated lymphoid tissue (MALT) for immune defense against pathogens encountered within the alimentary canal.