A student researching the etymological development of a word would find to be most helpful oxford dictionary thesaurus c American slang d shorter dictionary?

* Oxford Dictionary is known for its comprehensive coverage of word origins and historical usage. It provides detailed etymological entries, tracing words back to their earliest known forms and languages.

Let's look at why the other options aren't as helpful:

* Thesaurus: A thesaurus provides synonyms and antonyms. It doesn't focus on word history.

* American Slang: This focuses on informal language and would likely not offer detailed etymological information.

* Shorter Dictionary: While a shorter dictionary may have basic etymology information, it's unlikely to be as detailed or thorough as a comprehensive dictionary like the Oxford English Dictionary.

In summary: For in-depth etymological research, the Oxford Dictionary is the most helpful resource.