(A.) Nickel and oxygen reacting chemically could create a compound. (Most likely some sort of oxide)
The pure silver is only made up of one element, so it can't be a compound.
The sandwich and all it's components may contain chemical compounds, but is not a compound in itself.
While it is possible that the material the nails are made out of is a compound, we are not given this information. Simply stating that nails (no matter the size) are in a box, does not make it a compound.
Plucking occurs when rocks and stones become frozen to the base or sides of the glacier and are plucked from the ground or rock face as the glacier moves. HOPE THIS HELPS!~