Answer: a. maxillary sinuses only (but see explanation below).
Step-by-step explanation:
Maxillary and sphenoid paranasal sinuses are present since birth, and may thus be a source of clinical symptoms at any age. Frontal sinuses, in contrast, do not normally become aerated until age 6. Note that, unlike maxillary and frontal sinuses, the sphenoid sinuses are located deep within the facial skeleton and may not be palpated.