Question

give any two examples of universal set from the nature.​

Answer 1

A universal set (usually denoted by U) is a set which has elements of all the related sets, without any repetition of elements.

Say if A and B are two sets, such as A = {1,2,3} and B = {1,a,b,c}, then the universal set associated with these two sets is given by U = {1,2,3,a,b,c}.