Which of the following is an example of secondary source

Examples of secondary sources include:

journal articles that comment on or analyse research.

textbooks.

dictionaries and encyclopaedias.

books that interpret, analyse.

political commentary.

biographies.

dissertations.

newspaper editorial/opinion pieces.

Explanation:

“Secondary sources were created by someone who did not experience first-hand or participate in the events or conditions you're researching. For a historical research project, secondary sources are generally scholarly books and articles. A secondary source interprets and analyzes primary sources.”

the name of the theory is landmass theory.