You've probably noticed the person in your care becoming less able to make the simplest choices: What kind of cereal to eat? Which sweater to wear? What to do today? Before long, taking any kind of initiative will be impossible, as higher-order thinking becomes more damaged. While some inklings of preferences remain, indulge them to the best of your ability.
Don't rush to make all choices for the person. The actual choosing matters less than the pleasant feeling that can arise -- and carry over into other behaviors -- from being involved in social give-and-take.
Narrow the options. Present two choices: wheat flakes or oatmeal? Take a walk or feed the ducks?
Consider listing your personal first choice last: It's typical that the last word heard will be the one played back to you (oatmeal, ducks).
Skip intimidating open-ended questions. Not, "What do you want to do today?" Instead, "Should we take a drive today or feed the ducks?"