Beginner Exercise 276 / Solution
There are two eye spaces here, the left one promising two eyes.
After securing one eye, destroys the other eye. on a works, too, but leaves an additional ko-threat.
When Black secures the right eye first, destroys the left eye.
There is no chance for forcing a ko, because after , captures two stones.
After , White killing the left eye first is not a good idea, because creates another potential eye.