Final answer:
The correct answer is C. Cleft lip, which is a developmental defect where the upper lip does not fuse properly, leaving a gap.
Step-by-step explanation:
A cleft is 'a fault occurring along the developmental groove.' The correct answer to this question is C. Cleft lip. A cleft lip is a developmental defect that involves a partial or complete failure of the right and left portions of the upper lip to fuse together, leaving a cleft (gap).
A more severe developmental defect, a cleft palate, affects the hard palate, which is the bony structure separating the nasal cavity from the oral cavity. This defect arises when there's a failure in the fusion of the two halves of the hard palate to come together at the midline, creating a gap that allows communication between the nasal and oral cavities. It is important to note that the term 'harelip' is considered outdated and may be derogatory, hence it’s essential to use the term cleft lip when referring to this condition.