To determine the correct range of radiant exposure wavelength used for assessing the resistance to weathering as per IS 17953 : 2023, let's analyze the given options in the context of material testing standards.

Weathering resistance testing for materials such as uPVC profiles typically involves simulating sunlight exposure, which predominantly falls within the ultraviolet (UV) and visible light range. The standard ultraviolet (UV) wavelength range that is generally used in weathering tests is from 300 nm to about 400 nm. Nonetheless, exposure can extend into the visible spectrum, which goes up to 800 nm.

1. Option Analysis:
   • 150 nm to 300 nm: This range primarily covers UV-C light, which is less commonly used in weathering tests due to being absorbed by Earth's atmosphere.
   • 300 nm to 800 nm (Correct Answer): This wavelength range includes UV-B, UV-A, and enters into visible light, aligning well with standard practices for simulating solar radiation in weathering tests.
   • 200 nm to 500 nm: Extends into the UV-A and early visible spectrum, but typically the focus is broader to include more of the visible light.
   • 50 nm to 150 nm: This is in the far ultraviolet range and not practical for such tests.
2. Given that the intent of weathering tests is to simulate sunlight exposure, the range of 300 nm to 800 nm comprehensively covers both UV and visible light parts of the spectrum.

Therefore, the correct answer is 300 nm to 800 nm, as it adequately represents the range used for weathering tests in accordance with IS 17953 : 2023.