Arrange the following electromagnetic waves in the decreasing order...

The electromagnetic spectrum, arranged in decreasing order of wavelength (or increasing order of frequency), is as follows:

Radio waves > Microwaves > Infrared > Visible light > Ultraviolet > X-rays > Gamma rays.

Comparing the given waves:
Microwaves (B) have the longest wavelength (approx. $10^{-2}\text{ m}$).
Infrared rays (D) have a shorter wavelength (approx. $10^{-4}\text{ m}$).
Ultraviolet rays (C) have an even shorter wavelength (approx. $10^{-8}\text{ m}$).
X-rays (A) have the shortest wavelength among the given options (approx. $10^{-10}\text{ m}$).

Therefore, the correct decreasing order of wavelengths is (B) > (D) > (C) > (A).

Answer: (B) > (D) > (C) > (A)