forms: show list A as multiline, combine with picklist B, save every A-B as a single C value

forms: show list A as multiline, combine with picklist B, save every A-B as a single C value

Hi,

how can I do the following form C?

There are two lists A and B. In form C, all A values are listed. There each A list value can be combined with one B value by a picklist. On submit, every single A-B combination is saved as single C value.

Thanks