In conversations/interactions, there are numbers in front of your options. It should be possible to select these options by pressing numbers on the keyboard. Both top row and numpad (when numpad is active)
I see three options:
1. Support 10 options and when there are more, require mouse use.
2. Support 10 options and when there are more, ignore/don't display the ones that are too many and maybe display a warning that tells the designer to change the number of options).
3. Allow to "scroll" thought "sets" of options when there are more than 10: divide options into packs of =<9 and make the last option ("10" on the first page) be a "[more]" option, that switches to the next set. The "[more]" option on the last set returns to the first set.