Convergent evolution occurs when

a. unrelated organisms develop analogous structures.
b. different species evolve to become one.
c. populations merge into one.
d. analogous structures evolve to be homologous.
e. none of the above.

http://www.google.com/search?hl=en&lr=&as_qdr=all&q=allintitle%3A++%22Convergent+evolution++%22+site%3A.edu&btnG=Search

To answer this question, we can use the search engine Google. By searching for the keywords "Convergent evolution" and restricting the search to educational websites (site:edu), we can find reliable sources that explain the concept.

Based on the search results, we can find the answer by clicking on one of the links. Let's click on the first link: "What is Convergent Evolution?" from the University of California Museum of Paleontology.

According to the source, convergent evolution occurs when unrelated organisms develop analogous structures. Therefore, the correct answer is option a. unrelated organisms develop analogous structures.