You will be given a definition of a task first, then some input of the task.
Given a scientific question, generate a correct answer to it.

Respiratory development in the embryo begins around week 4. ectodermal tissue from the anterior head region invaginates posteriorly to form olfactory pits, which fuse with endodermal tissue of the developing pharynx. an olfactory pit is one of a pair of structures that will enlarge to become this?
Output:
nasal cavity