The upper stratosphere consisting of the ozone layer, protects us from the sun's radiation that falls in the wavelength region of

We begin by recalling an important scientific fact: the ozone present in the upper stratosphere is most effective in absorbing the Sun’s ultraviolet (UV) radiation. Specifically, ozone molecules absorb radiation in the UV-B and part of the UV-C regions. These regions correspond to wavelengths shorter than the visible spectrum and fall roughly between $$200 \ \text{nm}$$ and $$315 \ \text{nm}.$$

Now, let us compare this essential wavelength range with the intervals given in the four options. We have:

Option A offers $$200 - 315 \ \text{nm},$$ which matches exactly with the range of UV radiation that the ozone layer blocks.

Option B gives $$600 - 750 \ \text{nm},$$ which lies in the red to near-infrared part of the visible spectrum and is therefore not the harmful UV range absorbed by ozone.

Option C lists $$400 - 550 \ \text{nm},$$ which corresponds to the violet-green visible light band, again not primarily stopped by ozone.

Option D proposes $$0.8 - 1.5 \ \text{nm},$$ which is in the X-ray region. Ozone does not principally target such high-energy, extremely short wavelengths; moreover, X-rays are mostly absorbed by the denser parts of Earth’s atmosphere, not by the ozone layer alone.

From this direct comparison, only Option A aligns perfectly with the scientifically established ozone-absorption window of $$200 - 315 \ \text{nm}.$$

Hence, the correct answer is Option A.