The correct option is C U={1,4,5,7,8,9,11,12,15}
Given sets A={4,8,9};B={1,4,8};C={1,9}
Now, the universal set of all these three sets should have all the elements from all these 3 sets.
Now, from the Options we see U={1,4,8,9};U={1,4,5,7,8,9};U={1,4,5,7,8,9,11,12,15}
These three can be the universal set for the three sets.