Answer: Option 'c' is correct.
Explanation:
Since we have given that
R={10,15,20}
and
S={20,25}
As we know that Intersection means that elements which are common to both the sets.
And it is denoted by '∩'.
So, R∩S={20}
As 20 is the only element that is common in both the sets.
Hence, option 'c' is correct.