Which of the following is the most correct regarding ethernet frames?

a$.$ As an ethernet frame is passed from point$-$to$-$point, it remains totally unchanged.

b$.$ As an ethernet frame is passed from point$-$to$-$point, only the source MAC address is changed.

c$.$ As an ethernet frame is passed from point$-$to$-$point, only the destination MAC address is

changed.

d$.$ As an ethernet frame is passed from point$-$to$-$point, both the source MAC address and the

destination MAC address changed.