Step 1: Imaging of the paranasal sinuses uses dedicated projections; picking the right one depends on where the sinus sits within the skull.
Step 2: The sphenoid sinus is positioned centrally and low at the cranial base, so a beam directed upward from beneath the chin to the top of the head is needed. That projection is the submentovertical or basal view, which displays the sphenoid air cell free of superimposition.
Step 3: By contrast, the occipito-mental projection (Water's) targets the maxillary antra, the occipito-frontal projection (Caldwell) targets the frontal sinus, and Towne's projection is reserved for posterior cranial structures.
Step 4: Matching the sphenoid sinus to its ideal projection leaves only one choice.
\[\boxed{\text{Basal view}}\]