Final answer:
Interviews with current patients are the least likely source of data for historical nursing research because they do not represent historical data. Diaries, newspapers, and official documents are more appropriate sources as they are primary or secondary sources that can reflect the period under study.
Step-by-step explanation:
The source LEAST likely to be a source of data in historical nursing research is c) Interviews with current patients. Historical nursing research typically relies on primary sources and secondary data, which can include diaries of nurses, newspaper articles from the period being studied, and official documents related to nursing practices or healthcare policies of that time. Interviews with current patients would not be suitable because they would represent contemporary views or experiences, not historical data. Some common research methods used in historical studies include analyzing primary sources like diary entries of individuals from a period under discussion (a) and secondary data analysis, which could involve examining the results of surveys or academic journals for relevant historical information.