Final answer:
For effective online research about Emily Dickinson's brother, the best search terms are 'Austin Dickinson, Emily Dickinson', as they provide specific and focused results.
Step-by-step explanation:
If you were searching the internet for information about Emily Dickinson's brother, Austin, the most effective search terms to use would be C) Austin Dickinson, Emily Dickinson. This set of search terms is specific and directly related to the person you are researching, which will help the search engine provide the most relevant results. By including both 'Austin Dickinson' and 'Emily Dickinson', you are narrowing down the search to ensure that the results will be associated with the family relationship, which can help to differentiate from other individuals who might have the same name.