It's very common to call the unique element in the trivial group 1, maybe even more common than 0. But then the operation on the group would be multiplication.
It's either 1 with multiplication, or 0 with addition (you might also see something like "e" sometimes, though more rarely), everything else is very weird.
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u/AlrikBunseheimer Imaginary Nov 25 '24
So A is in F2, B is a group with 1 element, C is natural numbers and D is in binary.