List the elements of the set of all letters in the word zero

{z, e, r, o}

Step-by-step explanation:

The letters of "zero" are "z", "e", "r", and "o". The set of letters in the word zero will be the set containing those letters:

{z, e, r, o}

If you like, you can put them in alphabetical order, though that is not necessary.

{e, o, r, z}