Correct Answer: Pathology

Solution : The correct solution is the first option.

Explanation : In choosing a one-word substitute for the group of words study of diseases, it's important to consider the specific field of study associated with diseases.

Pathology is the correct term, as it refers to the branch of medical science that deals with the study of diseases, their causes, processes, development, and consequences.

The correct one-word substitute is pathology .

The meanings of the other options are as follows:

• Anthology : This term refers to a collection of literary works, typically poems or stories.
• Etymology : This term relates to the study of the origins and history of words.
• Neurology : This term refers to the branch of medicine dealing with disorders of the nervous system.