What do we call the tendency to think of a hammer as only a tool to hammer nails and not as a weapon,a lever,or a weight to prop open a door

A)  functional fixedness
B)  unnecessary constraints 
C)  irrelevant information
D)  a mental set

Functional Fixedness

A cognitive bias that limits a person to using an object only in the way it is traditionally used, hindering problem-solving and creativity.

Hammer

A tool typically used to drive nails into, or pull nails from, some other object, generally involving a handle and a heavy head.