The correct match between the entries in column I and column II is:
$$\begin{array}{|l|l|l|l|}\hline & \text{I: Radiation} & & \text{II: Wavelength} \\ \hline \text{(a)} & \text{Microwave} & \text{(i)} & 100\ \text{m} \\ \hline \text{(b)} & \text{Gamma rays} & \text{(ii)} & 10^{-15}\ \text{m} \\ \hline \text{(c)} & \text{A.M. radio} & \text{(iii)} & 10^{-10}\ \text{m} \\ \hline \text{(d)} & \text{X-rays} & \text{(iv)} & 10^{-3}\ \text{m} \\ \hline \end{array}$$
Answer: (D) (a)-(iv), (b)-(ii), (c)-(i), (d)-(iii)
Typical wavelengths:
Microwaves: about $1$ mm to $30$ cm, so $10^{-3}$ m (iv).
Gamma rays: shorter than about $10^{-12}$ m, so $10^{-15}$ m (ii).
AM radio: hundreds of metres, so $100$ m (i).
X-rays: about $10^{-10}$ m (iii).
Match: (a)-(iv), (b)-(ii), (c)-(i), (d)-(iii).
Solution by Sreeraj P, M.Sc Physics