Normally when you type a) or i) or i. or 1) or similar at the beginning of the line, Word will recognise it and start a bullet list automatically. Press Enter at the end of the line and Word will auto-insert the next list element. That will take care of the indenting for you:
The red box in the image above highlights the unordered list, ordered/numbered list, multi-level list, decrease indent and increase indent buttons. Use those while creating your MCQ form.
If you want to align in a columnar fashion, either use tables (you can make the borders invisible if you like), or insert Left Tabs to align the options (click the Ruler once to insert a Left Tab, then while typing text press Tab to jump to the next Left Tab position):