The back of a spoon is bulged outward, so let us take a look at what we know from these answers:
a. concave
A concave surface is exactly what it sounds like. It is caved inward. So, no the back of a spoon is not a concave mirror.
b. convex
A convex surface is one that bulges outward, so it looks like this would suit the back of a spoon.
c. complex
A complex surface (in this case, a mirror) would be one that is made up of a multitude of smaller surfaces like the big one. There aren't a whole bunch of tiny bulges on the back of a spoon, so this is not the answer.
d. normal
A normal surface would be a flat plane, which does not suit the back of a spoon. A metal spatula maybe, but not a spoon.
The correct answer would be B. The back of a spoon is a convex mirror.
Hope that helped =)