Click the 'Import/ Export' button on the answer key interface and copy and paste (or type) the correct answers into the field and click ‘Save’.
The answers can be listed all on one line separated by commas or spaces, or list the answers one per line.
Image: Answer key Format supported in Import/Export function.
Once the answers have been saved, you can then update any of the answers or turn on advanced marking options.
GIF: Import Export > Type Answer Key > Save