Arrange the following in the ascending order of wavelength: A. Gamma rays $$(\lambda_1)$$, B. x-rays $$(\lambda_2)$$, C. Infrared waves $$(\lambda_3)$$, D. Microwaves $$(\lambda_4)$$. Choose the most appropriate answer from the options given below:

Electromagnetic waves are arranged according to frequency (or energy) and, inversely, according to wavelength $$\lambda$$ using the relation $$c = \nu \lambda$$, where $$c$$ is the speed of light and $$\nu$$ is the frequency.

Higher frequency $$\Rightarrow$$ lower wavelength, and lower frequency $$\Rightarrow$$ higher wavelength.

Typical order from the highest frequency (smallest $$\lambda$$) to the lowest frequency (largest $$\lambda$$) is:

$$\text{Gamma rays} \;(\gamma) \; \lt\; \text{X-rays} \;\lt\; \text{Ultraviolet} \;\lt\; \text{Visible} \;\lt\; \text{Infrared} \;\lt\; \text{Microwaves} \;\lt\; \text{Radio waves}$$

Using only the given categories:

$$\lambda_1\;(\text{Gamma rays}) \; \lt \; \lambda_2\;(\text{X-rays}) \; \lt \; \lambda_3\;(\text{Infrared}) \; \lt \; \lambda_4\;(\text{Microwaves})$$

Hence, the ascending (increasing) order of wavelength is
$$\lambda_1 \lt \lambda_2 \lt \lambda_3 \lt \lambda_4$$

This corresponds to Option C.