This screenshot shows the alphanumeric practise trail partially completed after the participant has selected "C" but before they have selected "4".

This resource can be downloaded or viewed using the link: tr_alnum_demox.png

If you have wget available (typically on linux systems), then you can also obtain a copy using the command

 wget  -nd  biobank.ndph.ox.ac.uk/ukb/ukb/images/tr_alnum_demox.png