How can you relazie a perfect balck body in pratice​

A perfectly blackbody can't be realized in practice . The nearest approach to a perfectly blackbody is a surface coated with lamp black , platinum black , such a surface absorbs % to 98 % of the incident radiation .

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The best answer is (a) which is universal law is in effect at all times. it is constantly at play in everything we do and governs our lives. it is also important to note that universal law applies to not only everything on earth, but everything in the universe as well, which is another reason why it is in effect at all times.