R1,R2,R3,R4 are string variables.
Set R1 to choose(a,b,c,d .......................,z)
Set R2 to choose(a,b,c,d .......................,z)
Set R3 to choose(a,b,c,d .......................,z)
Set R4 to choose(a,b,c,d .......................,z)
Using an Array or a list you can do this with a loop.
Set text to R1&R2&R3&R4