$"$On an island, there are two kinds of inhabitants, knights, who always tell the truth, and their opposites, knaves, who always lie. You encounter two people A and B$.$ Determine, if possible, what A and B are if they address in the ways described.

A says $"\text{'}$At least one of us is a knave"" and B says nothing."

$$ a$.$ A and B are Knights

$$ b$.$ A and B are Knaves

$$ c$.$ A is Knight, B is Knave

$$ d$.$ A is knave, B is Knight