The active elements of annular array transducers appear ______.

• A. Disc-like
• B. Ring-shaped
• C. Linear
• D. Curved

Answer: (A)

In annular array transducers, the active elements are arranged as concentric circular rings. When you look at the face of the transducer, the combined active area forms a circular, disc-shaped aperture that transmits into tissue. That circular footprint is what gives the appearance of a disc-like active region. Each individual element is ring-shaped, but the overall emitting surface presented to the tissue is circular, not linear or curved. The other shapes don’t fit because a linear or curved aperture describes different array geometries, and while the elements themselves are rings, the question is about the appearance of the active area as a whole, which is disc-like.