Question

tricky question

Answer 1

I would say grandmother.

Answer 2

If you see this as a separation of two sets, like there's "what it is" and there's "what there is to be called" and you map a function from "what it is" to "what there is to be called".


Then using the function once we see that the father of mother, a.k.a. maternal grandfather, produces ("is called") maternal uncle.