Answer #2

The correct answer is A: 0.5 cm.

Look at the figure shown.

The focus of the beam is where the highest lateral resolution will be as this is where the beam is the narrowest. The narrower the beam, the better the transducer can distinguish two objects that are close together, hence the higher the resolution. We know that at the focus the beam width is approximately half the diameter of the crystal of half of 1 cm which is 0.5 cm. None of the other answers are correct. We do not need to know the frequency of the transducer to answer this question.