I think something that may be easier to do although hard is to stop offering options.
When my MIL started to go downhill, my FIL still wanted her to decide, and it was very hard to get him to stop getting him to ask, but just to do. Do not ask milk or OJ anymore - just make the best decision now.
The hard part is that all decisions have to be made - from clothing to food to all - and I have to say is that a schedule helps. Schedule meals, bathing, activities, and make things very simple for your father.
Just make sure that you get help. This is a very rough thing to do alone. The mood swings are bad and very taxing and once the more physical issues (incontinence) come along, you will need more help. It is very hard to keep an adult clean. Infections are not fun.
Contact the local alzheimers chapter and get support and help you need. We got a case manager. Unfortunately for us, my FIL did not follow any of the advice and my MIL suffered for it.