Here is a collection of images for notation. If you are using these in a Cloze with drag and drop on Otus set the parameters under Response container (global) to 55px width and 250px height. You can play around with those settings if you like - those numbers work for me.
Clefs, Time Signatures, and Barlines
The following set is for use outside of the drag and drop in Otus. (If using the notes images from above as the drag options, and these as images outside the drag options)