Choose the word which is different from the rest.

The answer is E. Blacksmith.

An engineer is a person who designs, builds, or maintains engines, machines, or structures. An architect is a person who designs buildings and other structures. A mechanic is a person who repairs and maintains machines. A mason is a person who builds with stone or brick. A blacksmith is a person who forges metal objects.

The word “blacksmith” is different from the rest because it is the only word that refers to a person who works with metal. The other words refer to people who work with machines, structures, or other materials.