The u in the upper right corner stands for the

bigger set
universal set
infinite set
complement

Universal set

Step-by-step explanation:

We need to find U in the upper right corner stands for what

Option 1 : bigger set

We cannot say this a bigger set without comparing it with another sets and since it is also containing  another sets So, it is not said to be a bigger set.

Option 1 is wrong .

Option 2 : Universal Set

Definition of Universal Set : The set which contains all elements or all objects  and of which all other sets are subsets.

Since we can see that SET M and SET N are contained in SET U

Thus U is a universal set.

Option 2 is correct .

Option 3: infinite set

we can see in the figure that it is finite set .

So, it is not infinite set.

Option 3 is wrong .

Option 4: complement

it is not a complement set (refer given figure )

Option 4 is wrong .

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