Which kinds of handicap are we talking about? B and C sound like they're meant for people with impaired vision, while A sounds more like a feature for folks with impaired motor skills.
It's a mixture of both, a kind of muscular dystrophy.
Fixating letters is difficult, coordinating hand movement also.
Since gesture detection depends heavily on timing, it would be necessary to be able to switch to a "touch only" mode.
For choosing a book title a pictogram like interface would be a good solution.