All options at once or in steps

When presenting users with any number of options, would it be better to show all options at once, or break it down into steps?

Imagine you have a list of options;

• 1a
• 1b
• 2
• 3

One way of dealing with this could be to show all options at once, so four options total (1a, 1b, 2, 3). Another way to go could be to show 1, 2 and 3 and only show 1a and 1b when a user selects 1.

Which one is easier for a user to proces?

Note; I can vaguely remember something about 'eight choices at once is easier dan having four choices twice' but I am not sure where this came from or if it is true to begin with.

Thanks!