Question

Which of the following are sets?
A. 1,2,3
B. {1,2},3
C. {{1,},2},3
D. {1,{2,},3}
E. {1,2,a,b}.

Answer 1

In sets bracket are very important

Option a and d are sets

B and c are not sets

Answer 2

Step-by-step explanation:

E.{1,2,a,b}

It is because the elements of a set have to be within curly brackets or second brackets. But the elements of A,B,C & D are not in curly brackets and so they are not sets.