1. Given data

• Frequency of electromagnetic wave: $f = 3\ \text{GHz} = 3 \times 10^9\ \text{Hz}$
• Object size: $\dfrac{\lambda}{100}$, where $\lambda$ is the wavelength of the wave.

2. Find the wavelength in free space

For an electromagnetic wave in free space,

where $c = 3 \times 10^8\ \text{m/s}$.

So,

Thus the object size is

3. Compare object size with wavelength

The object size is much smaller than the wavelength:

4. Decide the relevant phenomenon

• Reflection is prominent when the obstacle/surface is large compared to wavelength.
• Refraction occurs when a wave passes from one medium to another.
• Diffraction is significant when aperture/obstacle size is comparable to wavelength.
• Scattering occurs when the obstacle/particle size is much smaller than the wavelength.

Since the object size is $\lambda/100$, i.e. much smaller than the wavelength, the wave will undergo scattering.

5. Evaluate options

• A: Reflection $\rightarrow$ Incorrect
• B: Refraction $\rightarrow$ Incorrect
• C: Diffraction $\rightarrow$ Incorrect
• D: Scattering $\rightarrow$ Correct

Therefore, the correct answer is:

6. Comparison with stored answer

Stored correct answer: D

My derived answer is also D, so they agree.