Which of the following represents the best lateral resolution?

• A. 15mm
• B. 6mm
• C. 0.06 cm
• D. 2cm

Answer: (C)

Lateral resolution is about how well you can distinguish two structures that are side by side, perpendicular to the ultrasound beam. It gets better when the beam width across the image is narrower—smaller beam width means you can separate closer objects more clearly.

Among the options, the best lateral resolution comes from the smallest beam width, because that represents the finest lateral detail you can resolve. The other choices correspond to wider beams, which blur adjacent structures and degrade lateral resolution. In practice, ways to improve this include using higher frequency transducers and better beam focusing to narrow the beam at the depth of interest.