Choose the word which is different from the rest.

The answer is E. Hireling.

A calf is a young cow, a cub is a young bear, a piglet is a young pig, and a duckling is a young duck. All of these words refer to young animals. A hireling is a person who is employed for wages, especially one who is not permanent or who is not considered to be a member of the regular staff.

A hireling is different from the other words in the list because it does not refer to a young animal. It refers to a person who is employed for wages.