The correct option is (C) 220.
Step-by-step explanation: Let, c, t and a represents the number of children, teenagers and adults that attended the concert.
Then, according t the given information, we have
Since number of teenagers is three-fourth of the number of children, so we have
So, from equations (i) and (ii), we get
and
Mutiplying equation (iii) by 5 and then subtracting equation (iv), we get
Therefore, from equation (III), we get
Thus, there are 220 adults who attended the concert.
Option (C) is correct.